Processes for production and purification of hydrofluoroolefins

ABSTRACT

Disclosed herein are processes for the production of hydrofluoroolefins by dehydrofluorination. Also disclosed herein are processes for separation of hydrofluoroolefins from hydrofluorocarbons and from hydrogen fluoride.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application claiming priority benefitof U.S. patent application Ser. No. 11/264,183, filed Nov. 1, 2005, nowallowed, which is a continuation-in-part of and claims priority benefitof U.S. patent application Ser. No. 11/259,901 filed Oct. 27, 2005, nowabandoned, which claims the benefit of U.S. Provisional PatentApplication No. 60/623,210, filed Oct. 29, 2004, all of which areincorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to the field of production andpurification of hydrofluoroolefin compounds. The present disclosurefurther relates to processes utilizing azeotrope compositions forseparation of hydrofluoroolefins from hydrofluorocarbons and hydrogenfluoride.

2. Description of Related Art

Chlorine-containing compounds such as chlorofluorocarbons (CFCs) areconsidered to be detrimental to the Earth's ozone layer. Many of thehydrofluorocarbons (HFCs), used to replace CFCs, have been found tocontribute to global warming. Therefore, there is a need to identify newcompounds that do not damage the environment, but also possess theproperties necessary to function as refrigerants, solvents, cleaningagents, foam blowing agents, aerosol propellants, heat transfer media,dielectrics, fire extinguishing agents, sterilants and power cycleworking fluids. Fluorinated olefins, especially those containing one ormore hydrogens in the molecule (referred to herein ashydrofluoroolefins) are being considered for use in some of theseapplications such as in refrigeration as well as in processes to makefluoropolymers.

1,1,3,3,3-Pentafluoropropene is a useful cure-site monomer inpolymerizations to form fluoroelastomers. U.S. Pat. Nos. 6,703,533,6,548,720, 6,476,281, 6,369,284, 6,093,859, and 6,031,141, as well aspublished Japanese patent applications JP 09095459 and JP 09067281, andWIPO publication WO 2004018093, disclose processes wherein1,1,1,3,3,3-hexafluoropropane is heated at temperatures below 500° C. inthe presence of catalyst to form 1,1,3,3,3-pentafluoropropene. Theselow-temperature catalytic routes are chosen because of the well-knowntendency for fluorocarbons to fragment at higher temperatures, e.g.,above 500° C. This is made clear in Chemistry of Organic FluorineCompounds, by Milos Hudlicky, 2^(nd) Revised Edition, Ellis Horwood PTRPrentice Hall [1992] p. 515: “Polyfluoroparaffins and especiallyfluorocarbons and other perfluoro derivates show remarkable heatstability. They usually do not decompose at temperatures below 300° C.Intentional decomposition, however, carried out at temperatures of500-800° C., causes all possible splits in their molecules and producescomplex mixtures which are difficult to separate.”

U.S. Patent Application Publication 2002/0032356 discloses a process forproducing the perfluorinated monomers tetrafluoroethylene andhexafluoropropylene in a gold-lined pyrolysis reactor.

The catalytic process has disadvantages, including catalyst preparation,start-up using fresh catalyst, catalyst deactivation, potential forplugging of catalyst-packed reactors with polymeric by-products,catalyst disposal or reactivation, and long reaction times that impose aspace/time/yield reactor penalty. It would be desirable to be able toproduce 1,1,3,3,3-pentafluoropropene from 1,1,1,3,3,3-hexafluoropropanein high yield by a non-catalytic process.

BRIEF SUMMARY OF THE INVENTION

One aspect relates to a process to produce a hydrofluoroolefincomprising dehydrofluorinating a hydrofluorocarbon containing at leastone hydrogen and at least one fluorine on adjacent carbons, therebyforming a product mixture comprising said hydrofluoroolefin, unreactedhydrofluorocarbon and hydrogen fluoride, wherein at least one of saidhydrofluoroolefin and said hydrofluorocarbon are present in said productmixture as an azeotrope composition with hydrogen fluoride.

A further aspect relates to a process for the separation of ahydrofluoroolefin from a hydrofluorocarbon wherein saidhydrofluoroolefin contains one less fluorine atom and one less hydrogenatom than said hydrofluorocarbon, said process comprising: a) forming amixture comprising hydrofluoroolefin, hydrofluorocarbon, and hydrogenfluoride; and b) subjecting said mixture to a distillation step forminga column distillate composition comprising an azeotrope ornear-azeotrope composition of hydrogen fluoride and hydrofluoroolefinessentially free of said hydrofluorocarbon.

A further aspect relates to a process for the separation of ahydrofluoroolefin from a mixture comprising an azeotrope ornear-azeotrope composition of said hydrofluoroolefin and hydrogenfluoride, said process comprising: a) subjecting said mixture to a firstdistillation step in which a composition enriched in either (i) hydrogenfluoride or (ii) hydrofluoroolefin is removed as a first distillatecomposition with a first bottoms composition being enriched in the otherof said components (i) or (ii); and b) subjecting said first distillatecomposition to a second distillation step conducted at a differentpressure in which the component enriched as first bottoms composition in(a) is removed as a second distillate composition with the secondbottoms composition of the second distillation step enriched in the samecomponent which was enriched in the first distillate composition.

A further aspect relates to a process for the purification ofhydrofluoroolefin from a mixture of hydrofluoroolefin,hydrofluorocarbon, and hydrogen fluoride, said process comprising: a)subjecting said mixture to a first distillation step to form a firstdistillate composition comprising an azeotrope or near-azeotropecomposition containing hydrofluoroolefin and hydrogen fluoride and afirst bottoms composition comprising hydrofluorocarbon; b) subjectingsaid first distillate to a second distillation step from which acomposition enriched in either (i) hydrogen fluoride or (ii)hydrofluoroolefin is removed as a second distillate composition with asecond bottoms composition being enriched in the other of saidcomponents (i) or (ii); and c) subjecting said second distillatecomposition to a third distillation step conducted at a differentpressure than the second distillation step in which the componentenriched in the second bottoms composition in (b) is removed as a thirddistillate composition with the third bottoms composition of the thirddistillation step enriched in the same component that was enriched inthe second distillate composition.

A further aspect relates to a process to produce a hydrofluoroolefincomprising: a) feeding a hydrofluorocarbon containing at least onehydrogen and at least one fluorine on adjacent carbons to a reactionzone for dehydrofluorination to form a reaction product compositioncomprising hydrofluoroolefin, unreacted hydrofluorocarbon and hydrogenfluoride; b) subjecting said reaction product composition to a firstdistillation step to form a first distillate composition comprising anazeotrope or near-azeotope composition containing hydrofluoroolefin andhydrogen fluoride and a first bottoms composition comprisinghydrofluorocarbon; c) subjecting said first distillate composition to asecond distillation step from which a composition enriched in either (i)hydrogen fluoride or (ii) hydrofluoroolefin is removed as a seconddistillate composition with a second bottoms composition being enrichedin the other of said components (i) or (ii); and d) subjecting saidsecond distillate composition to a third distillation step conducted ata different pressure than the second distillation step in which thecomponent enriched in the second bottoms composition in (c) is removedas a third distillate composition with the third bottoms composition ofthe third distillation step enriched in the same component that wasenriched in the second distillate composition.

A further aspect is for a hydrofluoroolefin selected from the groupconsisting of CF₂═C(CHF₂)₂, CHF═C(CHF₂)₂, CH₂═C(CH₂F)CF₃,CH₂═CFCF₂CF₂CF₃, CHF₂CF₂CF═CFCH₃, CF₃CF₂CF═CHCH₃, (CF₃)₂C═CFCHF₂,(CF₃)₂CFCF═CHCH₃, (CF₃)₂C═C(CH₃)₂, (CH₃)₂C═CFCF₂CF₃, C₂F₅CH═CHCF₂C₂F₅,CF₃CH═CHCF₂CF₂C₂F₅, CF₃CF₂CF₂CF₂CF═CHCH₃, CF₃CF₂CF₂CF═CHCH₂CH₃,(CH₃)₂C═CFCF₂CF₂CF₃, and CF₃CH═CFCH₂CF₃.

Another aspect provides a process for producing CF₃CH═CF₂ in the absenceof dehydrofluorination catalyst. In particular, this aspect comprisespyrolyzing CF₃CH₂CF₃ to make CF₃CH═CF₂. Pyrolyzing accomplishes thethermal decomposition of the CF₃CH₂CF₃, at a temperature greater thanabout 700° C.

This selective formation of CF₃CH═CF₂ embodies several unexpectedresults. First, it is surprising that the heat input of the pyrolysisprocess does not cause the CF₃CH₂CF₃ reactant to fragment to C-1, e.g.,methanes, and C-2, e.g., ethane and ethylene, compounds. Second, it issurprising that the CF₃CH═CF₂ product is stable under pyrolysisconditions and does not undergo further conversion to rearrangedproducts or to products containing fewer hydrogen and/or fluorine atoms.Third, it is surprising that the pyrolysis to form CF₃CH═CF₂ takes placewith high selectivity.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is a schematic flow diagram illustrating one embodiment forpracticing a two-column azeotropic distillation process.

FIG. 2 is a schematic flow diagram illustrating one embodiment forpracticing a process for production of hydrofluoroolefin.

DETAILED DESCRIPTION OF THE INVENTION

One aspect relates to processes to produce and processes to purifyhydrofluoroolefins. The processes to purify include processes toseparate hydrofluoroolefins from hydrogen fluoride and processes toseparate hydrofluoroolefins from hydrofluorocarbons and hydrogenfluoride, said processes utilizing azeotrope or near-azeotropecompositions.

A further aspect provides a process to produce a hydrofluoroolefincomprising dehydrofluorinating a hydrofluorocarbon containing at leastone hydrogen and at least one fluorine on adjacent carbons, therebyforming a product mixture comprising said hydrofluoroolefin, unreactedhydrofluorocarbon and hydrogen fluoride, wherein at least one of saidhydrofluoroolefin and said hydrofluorocarbon are present in said productmixture as an azeotrope composition with hydrogen fluoride.

The hydrofluoroolefins are acyclic compounds containing 3 to 8 carbonatoms, fluorine and hydrogen. Hydrofluoroolefins must also contain atleast one double bond and may be linear or branched. The acyclichydrofluoroolefins may be represented by the formula,C_(x)H_(a-1)F_(b-1), wherein x is an integer from 3 to 8, a is aninteger from 2 to (x+1), b is an integer from (x+1) to (2x) and whereina+b=2x+2. Representative hydrofluoroolefins include, but are not limitedto, trifluoropropenes, tetrafluoropropenes, pentafluoropropenes,tetrafluorobutenes, pentafluorobutenes, hexafluorobutenes,heptafluorobutenes, pentafluoropentenes, hexafluoropentenes,heptafluoropentenes, octafluoropentenes, nonafluoropentenes,hexafluorohexenes, heptafluorohexenes, octafluorohexenes,nonafluorohexenes, decafluorohexenes, undecafluorohexenes,heptafluoroheptenes, octafluoroheptenes, nonafluoroheptenes,decafluoroheptenes, undecafluoroheptenes, dodecafluoroheptenes,tridecafluoroheptenes, octafluorooctenes, nonafluorooctenes,decafluorooctenes, undecafluorooctenes, dodecafluorooctenes,tridecafluorooctenes, tetradecafluorooctenes, andpentadecafluorooctenes.

Also included are cyclic hydrofluoroolefins containing a total of 4 to 8carbon atoms including 4 to 6 carbon atoms in the ring. Cyclichydrofluoroolefins must also contain at least one double bond and mayhave branching on the ring. The cyclic hydrofluoroolefins may berepresented by the formula, C_(y)H_(c-1)F_(d-1), wherein y is an integerfrom 4 to 8, c is an integer from 2 to y, d in an integer from y to(2y−2) and wherein c+d=2y. Representative cyclic hydrofluoroolefinsinclude, but are not limited to, difluorocyclopropenes,trifluorocyclopropenes, trifluorocyclobutenes, tetrafluorocyclobutenes,pentafluorocyclobutenes, trifluoromethylcyclopropenes,tetrafluoromethylcyclopropenes, pentafluoromethylcyclopropenes,tetrafluorocyclopentenes, pentafluorocyclopentenes,hexafluorocyclopentenes, heptafluorocyclopentenes,tetrafluorodimethylcyclopropenes, pentafluorodimethylcyclopropenes,hexafluorodimethylcyclopropenes, heptafluorodimethylcyclopropenes,tetrafluoroethylcyclopropenes, pentafluoroethylcyclopropenes,hexafluoroethylcyclopropenes, heptafluoroethylcyclopropenes,tetrafluoromethylcyclobutenes, pentafluoromethylcyclobutenes,hexafluoromethylcyclobutenes, heptafluoromethylcyclobutenes,pentafluorocyclohexenes, hexafluorocyclohexenes,heptafluorocyclohexenes, octafluorocyclohexenes, nonafluorocyclohexenes,pentafluoromethylcyclopentenes, hexafluoromethylcyclopentenes,heptafluoromethylcyclopentenes, octafluoromethylcyclopentenes,nonafluoromethylcyclopentenes, pentafluorodimethylcyclobutenes,hexafluorodimethylcyclobutenes, heptafluorodimethylcyclobutenes,octafluorodimethylcyclobutenes, nonafluorodimethylcyclobutenes,pentafluoroethylcyclobutenes, hexafluoroethylcyclobutenes,heptafluoroethylcyclobutenes, octafluoroethylcyclobutenes,nonafluoroethylcyclobutenes, pentafluorotrimethylcyclopropenes,hexafluorotrimethylcyclopropenes, heptafluorotrimethylcyclopropenes,octafluorotrimethylcyclopropenes, and nonafluorotrimethylcyclopropenes.

The hydrofluoroolefins may exist as different configurational isomers orstereoisomers. Included are all single configurational isomers, singlestereoisomers or any combination thereof. For instance, HFC-1234ze(CF₃CH═CHF) is meant to represent the E-isomer, Z-isomer, or anycombination or mixture of both isomers in any ratio. Another example isHFC-1336mzz (CF₃CH═CHCF₃), by which is represented the E-isomer,Z-isomer, or any combination or mixture of both isomers in any ratio.

The hydrofluorocarbons are acyclic, linear or branched compoundscontaining 3 to 8 carbon atoms, hydrogen and fluorine. At least onehydrogen atom and at least one fluorine atom must be on adjacent carbonatoms. The hydrofluorocarbons may be represented by the formulaC_(x)H_(a)F_(b), wherein x is an integer from 3 to 8, a is an integerfrom 2 to (x+1), b is an integer from (x+1) to (2x) and whereina+b=2x+2. The hydrofluorocarbons are precursor compounds for thehydrofluoroolefins. The hydrofluorocarbons may be dehydrofluorinated inthe vapor phase to form the hydrofluoroolefins of the present inventionalong with hydrogen fluoride co-product.

Also included are cyclic hydrofluorocarbons containing a total of 4 to 8carbon atoms and with the ring comprising 4 to 6 carbon atoms. At leastone hydrogen atom and at least one fluorine atom must be on adjacentcarbon atoms. The cyclic hydrofluorocarbons may be represented by theformula C_(y)H_(c)F_(d), wherein y is an integer from 4 to 8, c is aninteger from 2 to y, d is an integer from y to (2y−2) and whereinc+d=2y. The cyclic hydrofluorocarbons are precursor compounds for thecyclic hydrofluoroolefins. The cyclic hydrofluorocarbons may bedehydrofluorinated in the vapor phase to form the cyclichydrofluoroolefins of the present invention along with hydrogen fluorideco-product.

The list in Table 1 indicates representative hydrofluoroolefins and thecorresponding precursor hydrofluorocarbons. The list in Table 2indicates representative cyclic hydrofluoroolefins and the correspondingprecursor cyclic hydrofluorocarbons. Depending on the number andposition of hydrogen and fluorine atoms in a particular precursorhydrofluorocarbon, and provided that at least one hydrogen atom and atleast one fluorine atom must be on adjacent carbon atoms, more than onehydrofluoroolefin may be produced. Tables 1 and 2 indicate onerepresentative hydrofluoroolefin from a precursor hydrofluorocarbon andin some instances more than one hydrofluoroolefin from a precursorhydrofluorocarbon.

TABLE 1 Hydrofluorocarbon Hydrofluoroolefin(s) CF₃CF₂CH₂F CF₃CF═CHFCF₃CHFCHF₂ CF₃CF═CHF CF₃CH₂CF₃ CF₃CH═CF₂ CHF₂CF₂CH₂F CHF₂CF═CHFCHF₂CHFCHF₂ CHF₂CF═CHF CF₃CF₂CH₃ CF₃CF═CH₂ CF₃CHFCH₂F CF₃CF═CH₂CF₃CH₂CHF₂ CF₃CH═CHF CH₂FCF₂CH₂F CH₂FCF═CHF CH₃CF₂CHF₂ CHF₂CF═CH₂CHF₂CHFCH₂F CHF₂CF═CH₂ CF₃CH₂CH₂F CF₃CH═CH₂ CF₃CHFCH₃ CF₃CH═CH₂CHF₂CH₂CHF₂ CHF₂CH═CHF CH₂FCF₂CF₂CF₃ CHF═CFCF₂CF₃ CF₃CHFCF₂CHF₂CF₃CF═CFCHF₂ CF₃CH₂CF₂CF₃ CF₃CH═CFCF₃ CF₃CHFCHFCF₃ CF₃CH═CFCF₃CH₃CF₂CF₂CF₃ CH₂═CFCF₂CF₃ CH₂FCHFCF₂CF₃ CH₂═CFCF₂CF₃ CF₃CHFCF₂CH₂FCF₃CF═CFCH₂F CH₂FCF₂CF₂CHF₂ CHF═CFCF₂CHF₂ CHF₂CH₂CF₂CF₃ CHF₂CH═CFCF₃CHF₂CHFCHFCF₃ CHF₂CF═CHCF₃ and/or CHF₂CH═CFCF₃ CHF₂CHFCF₂CHF₂CHF₂CF═CFCHF₂ CHF₂CF₂CH₂CF₃ CHF₂CF═CHCF₃ CF₃CH₂CHFCF₃ CF₃CH═CHCF₃CF₃CHFCF₂CH₃ CF₃CF═CFCH₃ CF₃CF₂CHFCH₃ CF₃CF═CFCH₃ CH₃CF₂CF₂CHF₂CH₂═CFCF₂CHF₂ CF₃CH₂CF₂CH₂F CF₃CH═CFCH₂F CF₃CF₂CH₂CH₂F CF₃CF═CHCH₂Fand/or CF₃CF₂CH═CH₂ CH₂FCHFCHFCF₃ CH₂FCF═CHCF₃ and/or CH₂FCH═CFCF₃CHF₂CF₂CHFCH₂F CHF₂CF═CFCH₂F and/or CHF₂CF₂CF═CH₂ CF₃CH₂CH₂CF₃CF₃CH₂CH═CF₂ CHF₂CH₂CHFCF₃ CHF₂CH═CHCF₃ CHF₂CHFCH₂CF₃ CHF₂CH═CHCF₃CHF₂CH₂CF₂CHF₂ CHF₂CH═CFCHF₂ CHF₂CHFCHFCHF₂ CHF₂CH═CFCHF₂ CF₃CF₂CH₂CH₃CF₃CF═CHCH₃ CF₃CH₂CF₂CH₃ CF₃CH═CFCH₃ CH₃CHFCHFCF₃ CH₃CF═CHCF₃ and/orCH₃CH═CFCF₃ CH₃CHFCF₂CHF₂ CH₃CF═CFCHF₂ CH₂FCH₂CHFCF₃ CH₂FCH═CHCF₃CH₂FCHFCH₂CF₃ CH₂FCH═CHCF₃ CH₂FCH₂CF₂CHF₂ CH₂FCH═CFCHF₂ CH₂FCHFCHFCHF₂CH₂FCF═CHCHF₂ and/or CH₂FCH═CFCHF₂ CHF₂CH₂CH₂CF₃ CHF═CHCH₂CF₃CHF₂CH(CF₃)₂ CHF═C(CF₃)₂ CH₂FCF(CF₃)₂ CHF═C(CF₃)₂ CH₃CF(CF₃)₂CH₂═C(CF₃)₂ CH₂FCH(CF₃)₂ CH₂═C(CF₃)₂ CHF₂CF(CHF₂)₂ CF₂═C(CHF₂)₂CH₃CH(CF₃)₂ CF₂═C(CF₃)CH₃ CF₃CH(CH₂F)₂ CH₂═C(CF₃)CH₂F CHF₂CH(CHF₂)₂CHF═C(CHF₂)₂ CH₃CF(CHF₂)₂ CH₂═C(CHF₂)₂ CH₂FCH(CH₂F)CF₃ CH₂═C(CH₂F)CF₃CH₂FCH(CHF₂)₂ CH₂═C(CHF₂)₂ CF₃CHFCHFCF₂CF₃ CF₃CH═CFCF₂CF₃ and/orCF₃CF═CHCF₂CF₃ CF₃CF₂CH₂CF₂CF₃ CF₃CF₂CH═CFCF₃ CF₃CH₂CF₂CF₂CF₃CF₃CH═CFCF₂CF₃ CF₃CH₂CHFCF₂CF₃ CF₃CH═CHCF₂CF₃ CF₃CHFCH₂CF₂CF₃CF₃CH═CHCF₂CF₃ CH₃CF₂CF₂CF₂CF₃ CH₂═CFCF₂CF₂CF₃ CH₃CF₂CF₂CF₂CHF₂CH₂═CFCF₂CF₂CHF₂ CF₃CH₂CF₂CH₂CF₃ CF₃CH═CFCH₂CF₃ CHF₂CF₂CF₂CHFCH₃CHF₂CF₂CF═CFCH₃ CF₃CF₂CF₂CH₂CH₃ CF₃CF₂CF═CHCH₃ (CF₃)₂CFCH₂CF₃(CF₃)₂C═CHCF₃ (CF₃)₂CHCHFCF₃ (CF₃)₂C═CHCF₃ (CF₃)₂CFCHFCHF₂(CF₃)₂C═CFCHF₂ (CF₃)₂CFCH₂CHF₂ (CF₃)₂C═CHCHF₂ (CF₃)₂CFCH₂CH₃(CF₃)₂C═CHCH₃ CF₃CF₂CHFCHFCF₂CF₃ CF₃CF₂CH═CFCF₂CF₃ CH₂FCHFCF₂CF₂CF₂CF₃CH₂═CFCF₂CF₂CF₂CF₃ CF₃CH₂CHFCF₂CF₂CF₃ CF₃CH═CHCF₂CF₂CF₃CF₃CHFCH₂CF₂CF₂CF₃ CF₃CH═CHCF₂CF₂CF₃ CF₃CF₂CH₂CHFCF₂CF₃CF₃CF₂CH═CHCF₂CF₃ CF₃CH₂CF₂CF₂CH₂CF₃ CF₃CH═CFCF₂CH₂CF₃CF₃CF₂CH₂CH₂CF₂CF₃ CF₃CF═CHCH₂CF₂CF₃ CH₃CH₂CF₂CF₂CF₂CF₃CH₃CH═CFCF₂CF₂CF₃ CH₃CHFCF₂CF₂CF₂CF₃ CH₂═CHCF₂CF₂CF₂CF₃CF₃CF₂CF₂CH₂CHFCH₃ CF₃CF₂CF₂CH═CHCH₃ (CF₃)₂CFCF₂CH₂CH₃ (CF₃)₂CFCF═CHCH₃(CF₃)₂CFCH₂CH₂CH₃ (CF₃)₂C═CHCH₂CH₃ (CF₃)₂CHCHFCF₂CF₃ (CF₃)₂C═CHCF₂CF₃(CF₃)₂CFCHFCHFCF₃ (CF₃)₂C═CFCHFCF₃ and/or (CF₃)₂CFCF═CHCF₃ and/or(CF₃)₂CFCH═CFCF₃ (CF₃)₂CHCH₂CF₂CF₃ (CF₃)₂CHCH═CFCF₃ (CF₃)₂CFCH(CH₃)₂(CF₃)₂C═C(CH₃)₂ (CH₃)₂CHCF₂CF₂CF₃ (CH₃)₂C═CFCF₂CF₃ C₂F₅CHFCHFCF₂C₂F₅C₂F₅CF═CHCF₂C₂F₅ and/or C₂F₅CH═CFCF₂C₂F₅ CF₃CHFCHFCF₂CF₂C₂F₅CF₃CF═CHCF₂CF₂C₂F₅ and/or CF₃CH═CFCF₂CF₂C₂F₅ C₂F₅CHFCH₂CF₂C₂F₅C₂F₅CH═CHCF₂C₂F C₂F₅CH₂CHFCF₂C₂F₅ C₂F₅CH═CHCF₂C₂F₅ CF₃CHFCH₂CF₂CF₂C₂F₅CF₃CH═CHCF₂CF₂C₂F₅ CF₃CH₂CHFCF₂CF₂C₂F₅ CF₃CH═CHCF₂CF₂C₂F₅CHF₂CF₂CF₂CF₂CF₂CF₂CH₃ CHF₂CF₂CF₂CF₂CF₂CF═CH₂ CF₃CF₂CF₂CF₂CF₂CH₂CH₃CF₃CF₂CF₂CF₂CF═CHCH₃ CF₃CF₂CF₂CF₂CH₂CH₂CH₃ CF₃CF₂CF₂CF═CHCH₂CH₃CF₃CF₂C(CH₃)HCH₂CF₂CF₃ CF₃CF₂CH(CH₃)CH═CFCF₃ (CH₃)₂CHCF₂CF₂CF₂CF₃(CH₃)₂C═CFCF₂CF₂CF₃ C₂F₅CHFCHFCF₂CF₂C₂F₅ C₂F₅CF═CHCF₂CF₂C₂F₅ and/orC₂F₅CH═CFCF₂CF₂C₂F₅ C₂F₅CF₂CHFCHFCF₂C₂F₅ C₂F₅CF₂CF═CHCF₂C₂F₅CF₃(CF₂)₅CH₂CH₂F CF₃(CF₂)₅CH═CH₂ CF₃(CF₂)₅CH₂CH₃ CF₃(CF₂)₄CF═CHCH₃CF₃(CF₂)₃CH₂CH₂CHFCH₃ CF₃(CF₂)₃CH₂CH₂CH═CH₂ and/or CF₃(CF₂)₃CH₂CH═CHCH₃

TABLE 2 Hydrofluorocarbon Hydrofluoroolefin cyclo-CF₂CF₂CF₂CH₂—cyclo-CF₂CF₂CF═CH— cyclo-CF₂CF₂CHFCHF— cyclo-CF₂CF₂CF═CH—cyclo-CF₂CF₂CH₂CH₂— cyclo-CF₂CH₂CH═CF— cyclo-CF₂CF₂CF₂CHFCHF—cyclo-CF₂CF₂CF₂CF═CH— cyclo- cyclo-CF₂CF₂CF₂CF₂CF═CH—CF₂CF₂CF₂CF₂CHFCHF— cyclo- cyclo-CF₂CF₂CHFCF₂CF═CF— CF₂CF₂CHFCF₂CF₂CHF—

The hydrofluorocarbons are available commercially, may be made bymethods known in the art, or may be made as described herein.

1,1,1,2,3,3-Hexafluoro-2-(trifluoromethyl)-pentane ((CF₃)₂CFCF₂CH₂CH₃)may be prepared by the reaction of1,1,1,2,3,3-hexafluoro-2-(trifluoromethyl)-3-iodo-propane with ethyleneto give 1,1,1,2,3,3-hexafluoro-2-(trifluoromethyl)-5-iodopentanefollowed by zinc reduction in an acid such as HCl or acetic acid.

1,1,1,2-Tetrafluoro-2-(trifluoromethyl)-pentane ((CF₃)₂CFCH₂CH₂CH₃) maybe prepared by reacting methyl perfluoroisobutyrate with ethyl magnesiumbromide followed by hydrolysis to give1,1,1,2-tetrafluoro-2-(trifluoromethyl)-3-pentanol. The pentanol isconverted to 4,5,5,5-tetrafluoro-4-(trifluoromethyl)-2-pentene bydehydration with phosphorous pentoxide and the double bond saturated byhydrogenation over a palladium on carbon catalyst.

1,1,1,2,2,3,3,4,4,5,5-Undecafluoroheptane (CF₃CF₂CF₂CF₂CF₂CH₂CH₃) may beprepared by reaction of1,1,1,2,2,3,3,4,4,5,5-undecafluoro-5-iodo-pentane with ethylene to give1,1,1,2,2,3,3,4,4,5,5-undecafluoro-7-iodo-heptane followed by zincreduction in an acid such as HCl or acetic acid.

As mentioned earlier, certain precursor hydrofluorocarbons listed inTables 1 and also in Table 2 may produce a single hydrofluoroolefin or amixture of 2 or more hydrofluoroolefins as a result of thedehydrofluorination reaction. Included are the pairs of thehydrofluorocarbon and each hydrofluoroolefin individually or thehydrofluorocarbon and the mixtures of 2 or more hydrofluoroolefincompounds that may be produced by any specific reaction.

Anhydrous hydrogen fluoride (HF) is also useful in the processes and iscommercially available.

One aspect relates to a process to produce a hydrofluoroolefincomprising dehydrofluorinating a hydrofluorocarbon containing at leastone hydrogen and at least one fluorine on adjacent carbons, therebyforming a product mixture comprising said hydrofluoroolefin, unreactedhydrofluorocarbon and hydrogen fluoride, wherein at least one of saidhydrofluoroolefin and said hydrofluorocarbon are present in said productmixture as an azeotrope composition with hydrogen fluoride.

The dehydrofluorination of a hydrofluorocarbon may be carried out in thevapor phase. Vapor phase dehydrofluorination of a hydrofluorocarbon maybe suitably carried out using typical dehydrofluorination catalysts.Generally, the present dehydrofluorination may be carried out using anydehydrofluorination catalyst known in the art. These catalysts include,but are not limited to, aluminum fluoride; fluorided alumina; metals onaluminum fluoride; metals on fluorided alumina; oxides, fluorides, andoxyfluorides of magnesium, zinc and mixtures of magnesium and zincand/or aluminum; lanthanum oxide and fluorided lanthanum oxide; chromiumoxides, fluorided chromium oxides, and cubic chromium trifluoride;carbon, acid-washed carbon, activated carbon, three dimensional matrixcarbonaceous materials; and metal compounds supported on carbon. Themetal compounds are oxides, fluorides, and oxyfluorides of at least onemetal selected from the group consisting of sodium, potassium, rubidium,cesium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium,chromium, iron, cobalt, rhodium, nickel, copper, zinc, and mixturesthereof.

Dehydrofluorination catalysts include aluminum fluoride, fluoridedalumina, metals on aluminum fluoride, and metals on fluorided alumina,as disclosed in U.S. Pat. No. 5,396,000, incorporated herein byreference. Fluorided alumina and aluminum fluoride can be prepared asdescribed in U.S. Pat. No. 4,902,838, incorporated herein by reference.Suitable metals include chromium, magnesium (e.g., magnesium fluoride),Group VIIB metals (e.g., manganese), Group IIIB metals (e.g.,lanthanum), and zinc. In use, such metals are normally present ashalides (e.g., fluorides), as oxides and/or as oxyhalides. Metals onaluminum fluoride and metals on fluorided alumina can be prepared byprocedures as described in U.S. Pat. No. 4,766,260, incorporated hereinby reference. In one embodiment, when supported metals are used, thetotal metal content of the catalyst is from about 0.1 to 20 percent byweight, typically from about 0.1 to 10 percent by weight. Preferredcatalysts include catalysts consisting essentially of aluminum fluorideand/or fluorided alumina.

Additionally, dehydrofluorination catalysts include oxides, fluorides,and oxyfluorides of magnesium, zinc and mixtures of magnesium and zincand/or aluminum. A suitable catalyst may be prepared, for example bydrying magnesium oxide until essentially all water is removed, e.g., forabout 18 hours at about 100° C. The dried material is then transferredto the reactor to be used. The temperature is then gradually increasedto about 400° C. while maintaining a flow of nitrogen through thereactor to remove any remaining traces of moisture from the magnesiumoxide and the reactor. The temperature is then lowered to about 200° C.and a fluoriding agent, such as HF, or other vaporizable fluorinecontaining compounds such as HF, SF₄, CCl₃F, CCl₂F₃, CHF₃, CHClF₂ orCCl₂FCClF₂, optionally diluted with an inert gas such as nitrogen, ispassed through the reactor. The inert gas or nitrogen can be graduallyreduced until only HF or other vaporizable fluorine containing compoundsis being passed through the reactor. At this point, the temperature canbe increased to about 450° C. and held at that temperature to convertthe magnesium oxide to a fluoride content corresponding to at least 40percent by weight, e.g., for 15 to 300 minutes, depending on thefluoriding agent flowrate and the catalyst volume. The fluorides are inthe form of magnesium fluoride or magnesium oxyfluoride; the remainderof the catalyst is magnesium oxide. It is understood in the art thatfluoriding conditions such as time and temperature can be adjusted toprovide higher than 40 percent by weight fluoride-containing material.

Another suitable procedure for the catalyst preparation is to addammonium hydroxide to a solution of magnesium nitrate and, if present,zinc nitrate and/or aluminum nitrate. The ammonium hydroxide is added tothe nitrate solution to a pH of about 9.0 to 9.5. At the end of theaddition, the solution is filtered, the solid obtained is washed withwater, dried and slowly heated to 500° C., where it is calcined. Thecalcined product is then treated with a suitable fluorine-containingcompound as described above.

Yet another procedure for the preparation of metal (i.e., magnesium,optionally containing also zinc and/or aluminum) fluoride catalystscontaining one or more metal fluorides is to treat an aqueous solutionof the metal(s) halide(s) or nitrate(s) in deionized water with 48percent aqueous HF with stirring. Stirring is continued overnight andthe slurry evaporated to dryness on a steam bath. The dried solid isthen calcined in air at 400° C. for about four hours, cooled to roomtemperature, crushed and sieved to provide material for use in catalystevaluations.

Additionally, dehydrofluorination catalysts include lanthanum oxide andfluorided lanthanum oxide.

Suitable fluorided lanthanum oxide compositions may be prepared in anymanner analogous to those known to the art for the preparation offluorided alumina. For example, the catalyst composition can be preparedby fluorination of lanthanum oxide.

Suitable catalyst compositions may also be prepared by precipitation oflanthanum as the hydroxide, which is thereafter dried and calcined toform an oxide, a technique well known to the art. The resulting oxidecan then be pretreated as described herein.

The catalyst composition can be fluorinated to the desired fluorinecontent by pretreatment with a fluorine-containing compound at elevatedtemperatures, e.g., at about 200° C. to about 450° C. The pretreatmentwith a vaporizable fluorine-containing compound such as HF, SF₄, CCl₃F,CCl₂F₃, CHF₃, CHClF₂ or CCl₂FCClF₂ can be done in any convenient mannerincluding in the reactor which is to be used for carrying out thedehydrofluorination reaction. By vaporizable fluorine-containingcompound is meant a fluorine containing compound which, when passed overthe catalyst at the indicated conditions, will fluorinate the catalystto the desired degree.

A suitable catalyst may be prepared, for example, by drying La₂O₃ untilessentially all moisture is removed, e.g., for about 18 hours at about400° C. The dried catalyst is then transferred to the reactor to beused. The temperature is then gradually increased to about 400° C. whilemaintaining a flow of N₂ through the reactor to remove any remainingtraces of moisture from the catalyst and the reactor. The temperature isthen lowered to about 200° C. and the vaporizable fluorine-containingcompound is passed through the reactor. If necessary, nitrogen or otherinert gases can be used as diluents. The N₂ or other inert diluents canbe gradually reduced until only the vaporizable fluorine-containingcompound is being passed through the reactor. At this point thetemperature can be increased to about 450° C. and held at thattemperature to convert the La₂O₃ to a fluorine content corresponding toat least 80 percent LaF₃ by weight, e.g., for 15 to 300 minutes,depending on the flow of the fluorine containing compound and thecatalyst volume.

Another suitable procedure for the catalyst preparation is to addammonium hydroxide to a solution of La(NO₃)₃6H₂O. The ammonium hydroxideis added to the nitrate solution to a pH of about 9.0 to 9.5. At the endof the addition, the solution is filtered, the solid obtained is washedwith water, and slowly heated to about 400° C., where it is calcined.The calcined product is then treated with a suitable vaporizablefluorine-containing compound as described above.

Additionally, dehydrofluorination catalysts include chromium oxides,fluorided chromium oxides, and cubic chromium trifluoride. Cubicchromium trifluoride may be prepared from CrF₃XH₂O, where X is 3 to 9,preferably 4, by heating in air or an inert atmosphere (e.g., nitrogenor argon) at a temperature of about 350° C. to about 400° C. for 3 to 12hours, preferably 3 to 6 hours.

Cubic chromium trifluoride is useful by itself, or together with otherchromium compounds, as a dehydrofluorination catalyst. Preparation ofcubic chromium trifluoride is described in U.S. Pat. No. 6,031,141,incorporated herein by reference. Of note are catalyst compositionscomprising chromium wherein at least 10 weight percent of the chromiumis in the form of cubic chromium trifluoride, particularly catalystcompositions wherein at least 25 percent of the chromium is in the formof cubic chromium trifluoride, and especially catalyst compositionswherein at least 60 percent of the chromium is in the form of cubicchromium trifluoride. The chromium, including the cubic chromiumtrifluoride can be supported on and/or physically mixed with materialssuch as carbon, aluminum fluoride, fluorided alumina, lanthanumfluoride, magnesium fluoride, calcium fluoride, zinc fluoride and thelike. Preferred are combinations including cubic chromium trifluoride incombination with magnesium fluoride and/or zinc fluoride.

Additionally, dehydrofluorination catalysts include activated carbon, orthree dimensional matrix carbonaceous materials as disclosed in U.S.Pat. No. 6,369,284, incorporated herein by reference; or carbon ormetals such as sodium, potassium, rubidium, cesium, yttrium, lanthanum,cerium, praseodymium, neodymium, samarium, chromium, iron, cobalt,rhodium, nickel, copper, zinc, and mixtures thereof, supported on carbonas disclosed in U.S. Pat. No. 5,268,122, incorporated herein byreference. Carbon from any of the following sources are useful for theprocess of this invention; wood, peat, coal, coconut shells, bones,lignite, petroleum-based residues and sugar. Commercially availablecarbons which may be used include those sold under the followingtrademarks: Barneby & Sutcliffe™, Darco™, Nucharm, Columbia JXN™,Columbia LCK™, Calgon PCB, Calgon BPL™, Westvaco™, Norit™, and BarnabyCheny NB™.

Carbon includes acid-washed carbon (e.g., carbon which has been treatedwith hydrochloric acid or hydrochloric acid followed by hydrofluoricacid). Acid treatment is typically sufficient to provide carbon thatcontains less than 1000 ppm of ash. Suitable acid treatment of carbon isdescribed in U.S. Pat. No. 5,136,113, incorporated herein by reference.The carbon also includes three dimensional matrix porous carbonaceousmaterials. Examples are those described in U.S. Pat. No. 4,978,649,incorporated herein by reference. Of note are three dimensional matrixcarbonaceous materials which are obtained by introducing gaseous orvaporous carbon-containing compounds (e.g., hydrocarbons) into a mass ofgranules of a carbonaceous material (e.g., carbon black); decomposingthe carbon-containing compounds to deposit carbon on the surface of thegranules; and treating the resulting material with an activator gascomprising steam to provide a porous carbonaceous material. Acarbon-carbon composite material is thus formed.

The physical shape of the catalyst is not critical and may, for example,include pellets, powders or granules. Additionally, for catalystssupported on carbon, the carbon may be in the form of powder, granules,or pellets, or the like. Although not essential, catalysts that have notbeen fluorided may be treated with HF before use. It is thought thatthis converts some of the surface oxides to oxyfluorides. Thispretreatment can be accomplished by placing the catalyst in a suitablecontainer (which can be the reactor to be used to perform the reactionof the instant invention) and thereafter, passing HF over the driedcatalyst so as to partially saturate the catalyst with HF. This isconveniently carried out by passing HF over the catalyst for a period oftime (e.g., about 15 to 300 minutes) at a temperature of, for example,about 200° C. to about 450° C.

The catalytic dehydrofluorination may be suitably conducted at atemperature in the range of from about 200° C. to about 500° C., and, inanother embodiment, from about 300° C. to about 450° C. The contact timeis typically from about 1 to about 450 seconds, and, in anotherembodiment, from about 10 to about 120 seconds.

The reaction pressure can be subatmospheric, atmospheric orsuperatmostpheric. Generally, near atmospheric pressures are preferred.However, the dehydrofluorination can be beneficially run under reducedpressure (i.e., pressures less than one atmosphere).

The catalytic dehydrofluorination can optionally be carried out in thepresence of an inert gas such as nitrogen, helium, or argon. Theaddition of an inert gas can be used to increase the extent ofdehydrofluorination. Of note are processes where the mole ratio of inertgas to hydrofluorocarbon undergoing dehydrofluorination is from about5:1 to about 1:1. Nitrogen is the preferred inert gas.

A further aspect provides a process for the manufacture of ahydrofluoroolefin by dehydrofluorination of a hydrofluorocarbon in areaction zone at elevated temperature in the absence of catalyst.

In the present embodiment of dehydrofluorination, thedehydrofluorination of hydrofluorocarbon can be carried out in areaction zone at an elevated temperature in the absence of a catalyst asdescribed below in the description for the pyrolysis of CF₃CH₂CF₃ toCF₂═CHCF₃ and HF. Appropriate temperatures may be between about 350° C.and about 900° C., and, in another embodiment, between about 450° C. andabout 900° C. The residence time of gases in the reaction zone istypically from about 0.5 to about 60 seconds, and, in anotherembodiment, from about 2 seconds to about 20 seconds.

The reaction pressure for the dehydrofluorination reaction at elevatedtemperature in the absence of catalyst may be subatmospheric,atmospheric, or superatmospheric. Generally, near atmospheric pressuresare preferred. However, the dehydrofluorination can be beneficially rununder reduced pressure (i.e., pressures less than one atmosphere).

The dehydrofluorination at an elevated temperature in the absence of acatalyst may optionally be carried out in the presence of an inert gassuch as nitrogen, helium or argon. The addition of an inert gas can beused to increase the extent of dehydrofluorination. Of note areprocesses where the mole ratio of inert gas to the hydrofluorocarbonundergoing dehydrofluorination is from about 5:1 to about 1:1. Nitrogenis the preferred inert gas.

The reaction zone for either catalyzed or non-catalyzeddehydrofluorination may be a reaction vessel fabricated from nickel,iron, titanium or their alloys, as described in U.S. Pat. No. 6,540,933,incorporated herein by reference. A reaction vessel of these materials(e.g., a metal tube) optionally packed with the metal in suitable formmay also be used. When reference is made to alloys, it is meant a nickelalloy containing from about 1 to about 99.9 weight percent nickel, aniron alloy containing about 0.2 to about 99.8 weight percent iron, and atitanium alloy containing about 72 to about 99.8 weight percenttitanium. Of note is the use of an empty (unpacked) reaction vessel madeof nickel or alloys of nickel such as those containing about 40 weightpercent to about 80 weight percent nickel, e.g., Inconel™ 600 nickelalloy, Hastelloy™ C617 nickel alloy or Hastelloy™ C276 nickel alloy.

When used for packing, the metal or metal alloys may be particles orformed shapes such as, for example, perforated plates, rings, wire,screen, chips, pipe, shot, gauze, or wool.

The product mixture resulting from the dehydrofluorination ofhydrofluorocarbon will contain hydrofluoroolefin, unreactedhydrofluorocarbon and hydrogen fluoride. The amount of unreactedhydrofluorocarbon will depend upon the percent conversion achieved inthe reaction.

It has been discovered and is disclosed in co-owned, co-pending U.S.provisional patent applications, attorney docket numbers FL-1158,FL-1160, FL-1161, FL-1169, FL-1188 and FL-1195, that hydrofluoroolefinsmay form azeotrope or near-azeotrope compositions with hydrogenfluoride. These azeotrope and near-azeotrope compositions are useful inprocesses to produce hydrofluoroolefins and in processes to separatehydrofluoroolefins from hydrogen fluoride and hydrofluorocarbons.

As recognized in the art, an azeotrope or a near-azeotrope compositionis an admixture of two or more different components which, when inliquid form under a given pressure, will boil at a substantiallyconstant temperature, which temperature may be higher or lower than theboiling temperatures of the individual components, and which willprovide a vapor composition essentially identical to the liquidcomposition undergoing boiling.

For the purpose of this discussion, near-azeotrope composition (alsocommonly referred to as an “azeotrope-like composition”) means acomposition that behaves like an azeotrope (i.e., has constant boilingcharacteristics or a tendency not to fractionate upon boiling orevaporation). Thus, the composition of the vapor formed during boilingor evaporation is the same as or substantially the same as the originalliquid composition. Hence, during boiling or evaporation, the liquidcomposition, if it changes at all, changes only to a minimal ornegligible extent. This is to be contrasted with non-near-azeotropecompositions in which during boiling or evaporation, the liquidcomposition changes to a substantial degree.

Additionally, near-azeotrope compositions exhibit dew point pressure andbubble point pressure with virtually no pressure differential. That isto say that the difference in the dew point pressure and bubble pointpressure at a given temperature will be a small value. It may be statedthat compositions with a difference in dew point pressure and bubblepoint pressure of less than or equal to 3 percent (based upon the bubblepoint pressure) may be considered to be a near-azeotrope.

Accordingly, the essential features of an azeotrope or a near-azeotropecomposition are that at a given pressure, the boiling point of theliquid composition is fixed and that the composition of the vapor abovethe boiling composition is essentially that of the boiling liquidcomposition (i.e., no fractionation of the components of the liquidcomposition takes place). It is also recognized in the art that both theboiling point and the weight percentages of each component of theazeotrope composition may change when the azeotrope or near-azeotropeliquid composition is subjected to boiling at different pressures. Thus,an azeotrope or a near-azeotrope composition may be defined in terms ofthe unique relationship that exists among the components or in terms ofthe compositional ranges of the components or in terms of exact weightpercentages of each component of the composition characterized by afixed boiling point at a specified pressure.

It should be understood that while an azeotrope or near-azeotropecomposition may exist at a particular ratio of the components at giventemperatures and pressures, the azeotrope composition may also exist incompositions containing other components. These additional componentsinclude the individual components of the azeotrope composition, saidcomponents being present as an excess above the amount being present asthe azeotrope composition. For example, the azeotrope of ahydrofluoroolefin and hydrogen fluoride may be present in a compositionthat has an excess of said hydrofluoroolefin, meaning that the azeotropecomposition is present and additional hydrofluoroolefin is also present.Also for example, the azeotrope of a hydrofluoroolefin and hydrogenfluoride as well as an azeotrope of the starting hydrofluorocarbon andhydrogen fluoride may be present in a composition that has an excess ofthe starting hydrofluorocarbon used for the dehydrofluorination reactionto produce said hydrofluoroolefin, meaning that the azeotropecomposition is present and additional starting hydrofluorocarbon is alsopresent. For instance, the azeotrope of HFC-1225ye (CF₃CF═CHF) andhydrogen fluoride may be present in a composition that has an excess ofHFC-1225ye, meaning that the azeotrope composition is present andadditional HFC-1225ye is also present. Also, for example, the azeotropeof HFC-1225ye (CF₃CF═CHF) and hydrogen fluoride may be present in acomposition that has an excess of a suitable starting hydrofluorocarbonfor the dehydrofluorination reaction, such as HFC-236ea, meaning thatthe azeotrope composition is present and additional HFC-236ea is alsopresent.

It has been discovered that both hydrofluoroolefins andhydrofluorocarbons may form azeotrope compositions with hydrogenfluoride. Generally, the hydrofluoroolefin/hydrogen fluoride azeotropecomposition will boil at a lower temperature than the correspondingprecursor hydrofluorocarbon/hydrogen fluoride azeotrope composition.Thus, it should be possible to separate the hydrofluoroolefin/hydrogenfluoride azeotrope from the hydrofluorocarbon/hydrogen fluorideazeotrope, or to separate the hydrofluoroolefin/hydrogen fluorideazeotrope from the hydrofluorocarbon by azeotropic distillation.

The present process to produce hydrofluoroolefin may further comprisethe step of distilling the product mixture to produce a distillatecomposition comprising an azeotrope composition containinghydrofluoroolefin and hydrogen fluoride.

The distillation step may additionally provide a column bottomscomposition comprising unconverted hydrofluorocarbon used in thedehydrofluorination reaction. There may additionally be some amount ofhydrogen fluoride present in the column bottoms composition. The amountof hydrogen fluoride in the hydrofluorocarbon from the bottom of thedistillation column may vary from about 50 mole percent to less than 1part per million (ppm, mole basis) depending on the manner in which thedehydrofluorination reaction is conducted.

One embodiment for operating the present distillation involves providingan excess of hydrofluoroolefin to the distillation column. If the properamount of hydrofluoroolefin is fed to the column, then all the hydrogenfluoride may be taken overhead as an azeotrope composition containinghydrofluoroolefin and hydrogen fluoride. Thus, the hydrofluorocarbonremoved from the column bottoms will be essentially free of hydrogenfluoride.

As described herein, by “essentially free of hydrogen fluoride” is meantthat the composition contains less than about 100 ppm (mole basis),preferably less than about 10 ppm and most preferably less than about 1ppm, of hydrogen fluoride.

A further aspect provides a process for the separation of ahydrofluoroolefin from a hydrofluorocarbon wherein saidhydrofluoroolefin contains one less fluorine atom and one less hydrogenatom than said hydrofluorocarbon, said process comprising forming amixture comprising hydrofluoroolefin, hydrofluorocarbon and hydrogenfluoride; and subjecting said mixture to a distillation step forming acolumn distillate composition comprising an azeotrope or near-azeotropecomposition of hydrogen fluoride and hydrofluoroolefin essentially freeof said hydrofluorocarbon.

As described herein, by “essentially free of said hydrofluorocarbon” ismeant that the composition contains less than about 100 ppm (molebasis), preferably less than about 10 ppm and most preferably less thanabout 1 ppm, of hydrofluorocarbon.

The present process to separate a hydrofluoroolefin from ahydrofluorocarbon may further form a column bottoms compositioncomprising hydrofluorocarbon used in the dehydrofluorination reaction.The column bottoms composition comprising hydrofluorocarbon may containsome amount of hydrogen fluoride. The amount of hydrogen fluoride in thehydrofluorocarbon from the bottom of the distillation column may varyfrom about 50 mole percent to less than 1 part per million (ppm, molebasis) depending on the manner in which the dehydrofluorination reactionis conducted.

One embodiment for operating the present distillation involves providingan excess of hydrofluoroolefin to the distillation column. If the properamount of hydrofluoroolefin is fed to the column, then all the hydrogenfluoride may be taken overhead as an azeotrope composition containinghydrofluoroolefin and hydrogen fluoride. Thus, the hydrofluorocarbonremoved from the column bottoms will be essentially free of hydrogenfluoride.

In the distillation step, the distillate composition exiting thedistillation column overhead comprising hydrogen fluoride andhydrofluoroolefin may be condensed using, for example, standard refluxcondensers. At least a portion of this condensed stream may be returnedto the top of the column as reflux. The ratio of the condensed material,which is returned to the top of the distillation column as reflux, tothe material removed as distillate is commonly referred to as the refluxratio. The specific conditions which may be used for practicing thedistillation step depend upon a number of parameters, such as thediameter of the distillation column, feed points, and the number ofseparation stages in the column, among others. The operating pressure ofthe distillation column may range from about 10 psi pressure to about300 psi (1380 kPa), normally about 20 psi to about 75 psi. Thedistillation column is typically operated at a pressure of about 25 psi(172 kPa). Normally, increasing the reflux ratio results in increaseddistillate stream purity, but generally the reflux ratio ranges between0.2/1 to 200/1. The temperature of the condenser, which is locatedadjacent to the top of the column, is normally sufficient tosubstantially fully condense the distillate that is exiting from the topof the column, or is that temperature required to achieve the desiredreflux ratio by partial condensation.

The column distillate composition comprising an azeotrope ornear-azeotrope composition of hydrogen fluoride and hydrofluoroolefin,essentially free of hydrofluorocarbon, may be treated to remove thehydrogen fluoride and provide pure hydrofluoroolefin as product. Thismay be accomplished, for example, by neutralization. However, theproduction of substantial amounts of scrubbing discharge can createaqueous waste disposal concerns. Thus, there remains a need for moreefficient, economical and environmentally viable processes to removehydrogen fluoride from this mixture.

It has been discovered that hydrofluoroolefins may be separated frommixtures of hydrofluoroolefins and hydrogen fluoride by a distillationprocess that takes advantage of changing azeotrope concentrations atdifferent temperatures and pressures.

Another aspect provides a process for the separation of ahydrofluoroolefin from a mixture comprising an azeotrope ornear-azeotrope composition of said hydrofluoroolefin and hydrogenfluoride, said process comprising: a) subjecting said mixture to a firstdistillation step in which a composition enriched in either (i) hydrogenfluoride or (ii) hydrofluoroolefin is removed as a first distillatecomposition with a first bottoms composition being enriched in the otherof said components (i) or (ii); and b) subjecting said first distillatecomposition to a second distillation step conducted at a differentpressure in which the component enriched as first bottoms composition in(a) is removed as a second distillate composition with the bottomscomposition of the second distillation step enriched in the samecomponent which was enriched in the first distillate composition.

The first column bottoms composition comprising hydrofluoroolefin may beproduced to be essentially free of hydrogen fluoride. Additionally, thesecond column bottoms sample comprising hydrogen fluoride may beproduced to be essentially free of hydrofluoroolefin.

As described herein, by “essentially free of hydrofluoroolefin” is meantthat the composition contains less than about 100 ppm (mole basis),preferably less than about 10 ppm and most preferably less than about 1ppm, of hydrofluoroolefin.

The process as described above takes advantage of the change inazeotrope composition at different pressures to effectuate theseparation of hydrofluoroolefin and hydrogen fluoride. The firstdistillation step may be carried out at high pressure relative to thesecond distillation step. At higher pressures, the hydrogenfluoride/hydrofluoroolefin azeotrope contains less hydrofluoroolefin.Thus, this high-pressure distillation step produces an excess ofhydrofluoroolefin, which boiling at a higher temperature than theazeotrope will exit the column as the column bottoms compositioncomprising hydrofluoroolefin. The first column distillate composition isthen fed to a second distillation step operating at lower pressure. Atthe lower pressure, the hydrogen fluoride/hydrofluoroolefin azeotropeshifts to lower concentrations of hydrogen fluoride. Therefore, in thissecond distillation step, there exists an excess of hydrogen fluoride.The excess hydrogen fluoride, having a boiling point higher than theazeotrope, exits the second distillation column as the column bottomscomposition comprising hydrogen fluoride.

The reverse of the process described in the preceding paragraph is alsopossible. The first distillation step may be carried out at a lowerpressure relative to the second distillation step. At lower pressure,the hydrogen fluoride/hydrofluoroolefin azeotrope contains less hydrogenfluoride. Thus, this low-pressure distillation step produces an excessof hydrogen fluoride, which boiling at a higher temperature than theazeotrope will exit the column as the bottoms composition comprisinghydrogen fluoride. The first column distillate composition is then fedto a second distillation step operating at higher pressure. At thehigher pressure, the hydrogen fluoride/hydrofluoroolefin azeotropeshifts to higher concentrations of hydrogen fluoride. Therefore, in thissecond distillation step, there exists an excess of hydrofluoroolefin.The excess hydrofluoroolefin, having a boiling point higher than theazeotrope, exits the second distillation column as the bottomscomposition.

In general, the dehydrofluorination of hydrofluorocarbons is anendothermic reaction and thus may be accomplished in a tubular reactorwith catalyst in the tubes and with a heating medium on the shellside ofthe reactor. Alternatively, a heat carrier may be used to permitadiabatic operation. Either essentially pure hydrofluorocarbon oressentially pure hydrofluoroolefin, both being produced by thedistillation processes described herein, may be recycled back to thereactor to serve as heat carrier. Hydrofluorocarbon is a preferred heatcarrier, as introduction of hydrofluoroolefin to the dehydrofluorinationreactor will result in a reduction in single-pass conversion ofhydrofluorocarbon.

In both the first and second distillation steps, the distillate exitingthe distillation column overhead comprising hydrogen fluoride andhydrofluoroolefin may be condensed using, for example, standard refluxcondensers. At least a portion of this condensed stream may be returnedto the top of the column as reflux. The specific conditions which may beused for practicing the distillation steps depend upon a number ofparameters, such as the diameter of the distillation column, feedpoints, and the number of separation stages in the column, among others.The operating pressure of the first distillation column may range fromabout 50 psi (345 kPa) pressure to about 225 psi (1550 kPa), normallyabout 50 psi (345 kPa) to about 100 psi (690 kPa). The firstdistillation column is typically operated at a pressure of about 75 psi(520 kPa). Normally, increasing the reflux ratio results in increaseddistillate stream purity, but generally the reflux ratio ranges between0.1/1 to 100/1. The temperature of the condenser, which is locatedadjacent to the top of the column, is normally sufficient tosubstantially fully condense the distillate that is exiting from the topof the column, or is that temperature required to achieve the desiredreflux ratio by partial condensation.

The operating pressure of the second distillation column may range fromabout 5 psi (34 kPa) pressure to about 50 psi (345 kPa), normally about5 psi (34 kPa) to about 20 psi (138 kPa). The second distillation columnis typically operated at a pressure of about 17 psi (117 kPa). Normally,increasing the reflux ratio results in increased distillate streampurity, but generally the reflux ratio ranges between 0.1/1 to 50/1. Thetemperature of the condenser, which is located adjacent to the top ofthe column, is normally sufficient to substantially fully condense thedistillate that is exiting from the top of the column, or is thattemperature required to achieve the desired reflux ratio by partialcondensation.

FIG. 1 is illustrative of one embodiment for practicing the presenttwo-column distillation process for the separation of hydrofluoroolefinand hydrogen fluoride. Referring to FIG. 1, a feed mixture derived froma prior azeotropic distillation comprising hydrogen fluoride andhydrofluoroolefin, is passed through line (540) to a multiple stagedistillation column (510), operating at a temperature of about 77° C.and a pressure of about 335 psi (2310 kPa). The bottoms of thedistillation column (510), containing essentially pure hydrofluoroolefinat a temperature of about 86° C. and a pressure of about 337 psi (2320kPa) is removed from the bottom of column (510) through line (566). Thedistillate from column (510), containing the hydrogenfluoride/hydrofluoroolefin azeotrope at a temperature of about 77° C.and a pressure of about 335 psi (2310 kPa) is removed from the top ofcolumn (510) and sent through line (570) to a multiple stagedistillation column (520). The distillate from column (520), containingthe hydrogen fluoride/hydrofluoroolefin azeotrope at a temperature ofabout −19° C. and a pressure of about 17 psi (117 kPa), is removed fromcolumn (520) through line (585) and is recycled back to column (510).The bottoms of column (520) containing essentially pure hydrogenfluoride at a temperature of about 26° C. and a pressure of about 19 psi(131 kPa) is removed through line (586).

A further aspect provides a process for the purification ofhydrofluoroolefin from a mixture of hydrofluoroolefin,hydrofluorocarbon, and hydrogen fluoride, said process comprising: a)subjecting said mixture to a first distillation step to form a firstdistillate composition comprising an azeotrope or near-azeotropecomposition containing hydrofluoroolefin and hydrogen fluoride and afirst bottoms composition comprising hydrofluorocarbon; b) subjectingsaid first distillate to a second distillation step from which acomposition enriched in either (i) hydrogen fluoride or (ii)hydrofluoroolefin is removed as a second distillate composition with asecond bottoms composition being enriched in the other of saidcomponents (i) or (ii); and c) subjecting said second distillatecomposition to a third distillation step conducted at a differentpressure than the second distillation step in which the componentenriched in the second bottoms composition in (b) is removed as a thirddistillate composition with a third bottoms composition enriched in thesame component that was enriched in the second distillate composition.

The present method may optionally further comprise recycling at leastsome portion of said second bottoms composition (hydrofluoroolefin) tosaid first distillation step. The recycle of hydrofluoroolefin willensure that all the hydrogen fluoride is taken overhead as the azeotropecomposition with the hydrofluoroolefin. Thus, the hydrofluorocarbonexiting the process as the first column bottoms composition may beproduced to be essentially free of hydrogen fluoride andhydrofluoroolefin. The hydrofluoroolefin exiting the process as thesecond column bottoms composition may be produced to be essentially freeof hydrogen fluoride. The hydrogen fluoride exiting the process as thethird column bottoms composition may be produced to be essentially freeof hydrofluoroolefin.

As described herein, by “essentially free of hydrogen fluoride andhydrofluoroolefin” is meant that the composition contains less thanabout 100 ppm (mole basis), preferably less than about 10 ppm and mostpreferably less than about 1 ppm, of each of hydrogen fluoride andhydrofluoroolefin.

The conditions for the first distillation step are the same as those forthe azeotropic distillation process for separation of hydrofluoroolefinfrom hydrofluorocarbon, described earlier herein. The conditions for thesecond and third distillation steps are the same as the conditions forthe 2 column process for separation of hydrofluoroolefin from hydrogenfluoride, also described earlier herein.

A further aspect provides a process to produce hydrofluoroolefincomprising: a) feeding hydrofluorocarbon containing at least onehydrogen and at least one fluorine on adjacent carbons to a reactionzone for dehydrofluorination to form a reaction product compositioncomprising hydrofluoroolefin, unreacted hydrofluorocarbon and hydrogenfluoride; b) subjecting said reaction product composition to a firstdistillation step to form a first distillate composition comprising anazeotrope or near-azeotrope composition containing hydrofluoroolefin andhydrogen fluoride and a first bottoms composition comprisinghydrofluorocarbon; c) subjecting said first distillate composition to asecond distillation step from which a composition enriched in either (i)hydrogen fluoride or (ii) hydrofluoroolefin is removed as a seconddistillate composition with a second bottoms composition being enrichedin the other of said components (i) or (ii); and d) subjecting saidsecond distillate composition to a third distillation step conducted ata different pressure than the second distillation step in which thecomponent enriched in the second bottoms composition in (c) is removedas a third distillate composition with a third bottoms compositionenriched in the same component that was enriched in the seconddistillate composition.

Optionally, the process may further comprise recycling at least someportion of said first bottoms composition (hydrofluorocarbon) to saidreaction zone. Optionally, the process may further comprise recycling atleast some portion of said second bottoms composition or said thirdbottoms composition (i.e. that which is hydrofluoroolefin) to saidreaction zone. Optionally, the process may further comprise recycling atleast some portion of said second bottoms composition or said thirdbottoms composition (i.e. that which is hydrofluoroolefin) to said firstdistillation step. Optionally, the process may further compriserecovering at least some portion of said second bottoms composition orsaid third bottoms composition as hydrofluoroolefin essentially free ofhydrofluorocarbon and hydrogen fluoride.

As described herein, by “essentially free of hydrofluorocarbon andhydrogen fluoride” is meant that the composition contains less thanabout 100 ppm (mole basis), preferably less than about 10 ppm and mostpreferably less than about 1 ppm, of each of hydrofluorocarbon andhydrogen fluoride.

FIG. 2 is illustrative of one embodiment for practicing the presentprocess for production of hydrofluoroolefin. Hydrofluorocarbon is fedthrough line (360) to reactor (320). The reactor effluent mixturecomprising hydrogen fluoride, hydrofluorocarbon and hydrofluoroolefin,exits the reactor through line (450) and is fed to a multiple stagedistillation column (410). The bottoms of distillation column (410),containing essentially pure hydrofluorocarbon is removed from the bottomof column 410) through line (466) and may be recycled back to thereactor. The distillate from column (410), containing the hydrogenfluoride/hydrofluoroolefin azeotrope is removed from the top of column(410) and is sent through line (540) to a second multiple stagedistillation column (510). The bottoms from column (510), which isessentially pure hydrofluoroolefin, is removed from column (510) throughline (566) and may be recycled back to the reactor (320) as a heatcarrier. The distillate from column (510), containing the hydrogenfluoride/hydrofluoroolefin azeotrope, is fed through line (570) to athird multiple stage distillation column (520). The distillate fromcolumn (520) comprising hydrogen fluoride/hydrofluoroolefin is removedthrough line (585) and may be recycled to the second distillation column(510). The bottoms composition from column (520) is essentially purehydrogen fluoride and is removed from column (520) through line (586).The essentially pure hydrogen fluoride product from this process may beused in any manner appropriate such as feeding to a fluorination reactorfor production of a fluorochemical compound, or may be neutralized fordisposal.

While not illustrated in the Figures, it is understood that certainpieces of process equipment may be used in the processes describedherein, for optimization. For instance, pumps, heaters or coolers may beused where appropriate. As an example, it is desirable to have the feedto a distillation column at the same temperature as the point in thecolumn that it is fed. Therefore, heating or cooling of the processstream may be necessary to match the temperature.

Another embodiment provides a process of producing CF₃CH═CF₂ bypyrolysis of CF₃CH₂CF₃. The process may be written as:CF₃CH₂CF₃+Δ→CF₃CH═CF₂+HFwhere Δ represents heat and HF is hydrogen fluoride.

Pyrolysis, as the term is used herein, means chemical change produced byheating in the absence of catalyst. Pyrolysis reactors generallycomprise three zones: a) a preheat zone, in which reactants are broughtclose to the reaction temperature; b) a reaction zone, in whichreactants reach reaction temperature and are at least partiallypyrolyzed, and products and any byproducts form; c) a quench zone, inwhich the stream exiting the reaction zone is cooled to stop thepyrolysis reaction. Laboratory-scale reactors have a reaction zone, butthe preheating and quenching zones may be omitted.

In this embodiment, the reactor may be of any shape consistent with theprocess but is preferably a cylindrical tube, either straight or coiled.Although not critical, such reactors typically have an inner diameter offrom about 1.3 to about 5.1 cm (about 0.5 to about 2 inches). Heat isapplied to the outside of the tube, the chemical reaction taking placeon the inside of the tube. The reactor and its associated feed lines,effluent lines and associated units should be constructed, at least asregards the surfaces exposed to the reaction reactants and products, ofmaterials resistant to hydrogen fluoride. Typical materials ofconstruction, well-known to the fluorination art, include stainlesssteels, in particular of the austenitic type, the well-known high nickelalloys, such as Monel® nickel-copper alloys, Hastelloy-based alloys andInconel® nickel-chromium alloys and copper clad steel. Where the reactoris exposed to high temperature the reactor may be constructed of morethan one material. For example, the outer surface layer of the reactorshould be chosen for ability to maintain structural integrity and resistcorrosion at the pyrolysis temperature, the inner surface layer of thereactor should be chosen of materials resistant to attack by, that is,inert to, the reactant and products. In the case of the present process,the product hydrogen fluoride is corrosive to certain materials. Inother words, the reactor may be constructed of an outer material chosenfor physical strength at high temperature and an inner material chosenfor resistance to corrosion by the reactants and products under thetemperature of the pyrolysis.

For the process of this embodiment, it is preferred that the reactorinner surface layer be made of high nickel alloy, that is an alloycontaining at least about 50 wt % nickel, preferably a nickel alloyhaving at least about 75 wt % nickel, more preferably a nickel alloyhaving less than about 8 wt % chromium, still more preferably a nickelalloy having at least about 98 wt % nickel, and most preferablysubstantially pure nickel, such as the commercial grade known as Nickel200. More preferable than nickel or its alloys as the material for theinner surface layer of the reactor is gold. The thickness of the innersurface layer does not substantially affect the pyrolysis and is notcritical so long as the integrity of the inner surface layer is intact.The thickness of the inner surface layer is typically from about 10 toabout 100 mils (0.25 to 2.5 mm). The thickness of the inner surfacelayer can be determined by the method of fabrication, the cost ofmaterials, and the desired reactor life.

The reactor outer surface layer is resistant to oxidation or othercorrosion and maintains sufficient strength at the reaction temperaturesto keep the reaction vessel from failing of distorting. This layer ispreferably Inconel® alloy, more preferably Inconel® 600.

The present pyrolysis of CF₃CH₂CF₃ to CF₂═CHCF₃ and HF is carried out inthe absence of catalyst in a substantially empty reactor. By absence ofcatalyst is meant that no material or treatment is added to thepyrolysis reactor that increases the reaction rate by reducing theactivation energy of the pyrolysis process. It is understood thatalthough surfaces that are unavoidably present in any containmentvessel, such as a pyrolysis reactor, may have incidental catalytic oranticatalytic effects on the pyrolysis process, the effect makes aninsignificant contribution, if any, to the pyrolysis rate. Morespecifically, absence of catalyst means absence of conventionalcatalysts having high surface area in a particulate, pellet, fibrous orsupported form that are useful in promoting the elimination of hydrogenfluoride from a hydrofluorocarbon (i.e., dehydrofluorination). Example,dehydrofluorination catalysts include: chromium oxide, optionallycontaining other metals, metal oxides or metal halides; chromiumfluoride, unsupported or supported; and activated carbon, optionallycontaining other metals, metal oxides or metal halides.

Substantially empty reactors useful for carrying out the present processare tubes comprising the aforementioned materials of construction.Substantially empty reactors include those wherein the flow of gasesthrough the reactor is partially obstructed to cause back-mixing, i.e.turbulence, and thereby promote mixing of gases and good heat transfer.This partial obstruction can be conveniently obtained by placing packingwithin the interior of the reactor, filling its cross-section or byusing perforated baffles. The reactor packing can be particulate orfibrillar, preferably in cartridge disposition for ease of insertion andremoval, has an open structure like that of Raschig Rings or otherpackings with a high free volume, to avoid the accumulation of coke andto minimize pressure drop, and permits the free flow of gas. Preferablythe exterior surface of such reactor packing comprises materialsidentical to those of the reactor inner surface layer; materials that donot catalyze dehydrofluorination of hydrofluorocarbons and are resistantto hydrogen fluoride. The free volume is the volume of the reaction zoneminus the volume of the material that makes up the reactor packing. Thefree volume is at least about 80%, preferably at least about 90%, andmore preferably about 95%.

The pyrolysis which accomplishes the conversion of CF₃CH₂CF₃ toCF₂═CHCF₃ is suitably conducted at a temperature of at least about 700°C., preferably at least about 750° C., and more preferably at leastabout 800° C. The maximum temperature is no greater than about 1,000°C., preferably no greater than about 950° C., and more preferably nogreater than about 900° C. The pyrolysis temperature is the temperatureof the gases inside at about the mid-point of the reaction zone.

The residence time of gases in the reaction zone is typically from about0.5 to about 60 seconds, more preferably from about 2 seconds to about20 seconds at temperatures of from about 700 to about 900° C. andatmospheric pressure. Residence time is determined from the net volumeof the reaction zone and the volumetric feed rate of the gaseous feed tothe reactor at a given reaction temperature and pressure, and refers tothe average amount of time a volume of gas remains in the reaction zone.

The pyrolysis is preferably carried out to a conversion of the CF₃CH₂CF₃at least about 25%, more preferably to at least about 35%, and mostpreferably to at least about 45%. By conversion is meant the portion ofthe reactant that is consumed during a single pass through the reactor.Pyrolysis is preferably carried out to a yield of CF₃CH═CF₂ of at leastabout 50%, more preferably at least about 60%, and most preferably atleast about 75%. By yield is meant the moles of CF₃CH═CF₂ produced permole of CF₃CH₂CF₃ consumed.

The reaction is preferably conducted at subatmospheric, or atmospherictotal pressure. That is, the reactants plus other ingredients are atsubatmospheric pressure or atmospheric pressure. (If inert gases arepresent as other ingredients, as discussed below, the sum of the partialpressures of the reactants plus such ingredients is subatmospheric oratmospheric). Near atmospheric total pressure is more preferred. Thereaction can be beneficially run under reduced total pressure (i.e.,total pressure less than one atmosphere).

The reaction according to this embodiment can be conducted in thepresence of one or more unreactive diluent gases, that is diluent gasesthat do not react under the pyrolysis conditions. Such unreactivediluent gases include the inert gases nitrogen, argon, and helium.Fluorocarbons that are stable under the pyrolysis conditions, forexample, trifluoromethane and perfluorocarbons, may also be used asunreactive diluent gases. It has been found that inert gases can be usedto increase the conversion of CF₃CH₂CF₃ to CF₃CH═CF₂. Of note areprocesses where the mole ratio of inert gas to CF₃CH₂CF₃ fed to thepyrolysis reactor is from about 5:1 to 1:1. Nitrogen is a preferredinert gas because of its comparatively low cost.

The present process produces a 1:1 molar mixture of HF and CF₃CH═CF₂ inthe reactor exit stream. The reactor exit stream can also containunconverted reactant, CF₃CH₂CF₃. The components of the reactor exitstream can be separated by conventional means, such as distillation.Hydrogen fluoride and CF₃CH═CF₂ form a homogenous low-boiling azeotropecontaining about 60 mole percent CF₃CH═CF₂. The present process reactorexit stream can be distilled and the low-boiling HF and CF₃CH═CF₂azeotrope taken off as a distillation column overhead stream, leavingsubstantially pure CF₃CH₂CF₃ as a distillation column bottom stream.Recovered CF₃CH₂CF₃ reactant may be recycled to the reactor. CF₃CH═CF₂can be separated from its azeotrope with HF by conventional procedures,such as pressure swing distillation or by neutralization of the HF withcaustic.

Without further elaboration, it is believed that one skilled in the artcan, using the description herein, utilize the disclosed compositionsand processes to their fullest extent. The following exemplaryembodiments are, therefore, to be construed as merely illustrative, anddo not constrain the remainder of the disclosure in any way whatsoever.

EXAMPLES Example 1 Dehydrofluorination of CF₃CH₂CHF₂ to CF₃CH═CHF (E andZ Isomers Over Carbonaceous Catalyst

A Hastelloy™ nickel alloy reactor (2.54 cm OD×2.17 cm ID×24.1 cm L) wascharged with 14.32 g (25 mL) of spherical (8 mesh) three dimensionalmatrix porous carbonaceous material prepared substantially as describedin U.S. Pat. No. 4,978,649, incorporated herein by reference. The packedportion of the reactor was heated by a 5″×1″ ceramic band heater clampedto the outside of the reactor. A thermocouple positioned between thereactor wall and the heater measured the reactor temperature. Aftercharging the reactor with the carbonaceous material, nitrogen (10ml/min, 1.7×10⁻⁷ m³/s) was passed through the reactor and thetemperature was raised to 200° C. during a period of one hour andmaintained at this temperature for an additional 4 hours. The reactortemperature was then raised to the desired operating temperature and aflow of CF₃CH₂CHF₂ and nitrogen was started through the reactor.

A portion of the total reactor effluent was sampled on-line for organicproduct analysis using a gas chromatograph equipped with a massselective detector (GC-MS); the results are summarized in Table 3. Thebulk of the reactor effluent containing organic products and alsoinorganic acid, such as HF, was treated with aqueous caustic forneutralization.

TABLE 3 Reactor CF₃CH₂CHF₂ Temp. feed N₂ feed GC Area Percent (° C.)(mL/min) (mL/min) E- CF₃CH═CHF Z- CF₃CH═CHF CF₃CH₂CHF₂ Unks 200 10 200.1 ND 99.6 0.3 250 10 20 0.8 ND 99.0 0.2 300 10 20 8.9 ND 90.9 0.2 35010 10 31.6 5.7 62.3 0.4 350 10 5 42.4 8.7 48.3 0.6 ND = not detected

Example 2 Dehydrofluorination of CF₃CH₂CHF₂ to CF₃CH═CHF (E and ZIsomers) Over Fluorided Alumina Catalyst

A 15 in (38.1 cm)×⅜ in (0.95 cm) Hastelloy tube was charged with 7.96grams (13 cc) of gamma-alumina ground to 12-20 mesh (0.84 to 1.68 mm).The catalyst was activated by heating at 200° C. for 15 minutes under anitrogen purge (50 sccm, 8.3×10⁻⁷ m³/s). The temperature was raised to325° C. for 10 minutes, to 400° C. for 20 minutes, and then lowered to300° C. for 60 minutes. The nitrogen flow was reduced to 35 sccm(5.8×10⁻⁷ m³/s) and anhydrous HF vapor was fed at 12 sccm (2.0×10⁻⁷m³/s) for 35 minutes. The temperature was then raised to 325° C. for 60minutes, to 350° C. for 60 minutes, to 375° C. for 90 minutes, to 400°C. for 30 minutes, and to 425° C. for 40 minutes. The nitrogen flow wasthen reduced to 25 sccm (4.2×10⁻⁷ m³/s) and the HF raised to 20 sccm(3.3×10⁻⁷ m³/s) for 20 minutes. The nitrogen flow was then reduced to 15sccm (2.5×10⁻⁷ m³/s) and the HF flow increased to 28 sccm (4.7×10⁻⁷m³/s) for 20 minutes. The nitrogen flow was then reduced to 5 sccm(8.3×10⁻⁸ m³/s) and the HF increased to 36 sccm (6.0×10⁻⁷ m³/s) for 20minutes. The nitrogen flow was then shut off, and the HF flow increasedto 40 sccm (6.7×10⁻⁷ m³/s) for 121 minutes.

The temperature of the reactor was set to 375° C., and CF₃CH₂CHF₂ wasfed at a flow rate of 5.46 mL/hour (20.80 sccm, 3.5×10⁻⁷ m³) andnitrogen co-fed at a flow rate of 5.2 sccm (8.7×10⁻⁸ m³). The effluentwas analyzed by GC; the results are summarized in Table 4.

TABLE 4 Component GC Area % E-CF₃CH═CHF 71.4 CF₃CH₂CHF₂ 15.2 Z-CF₃CH═CHF12.1 unknown 1.3

Example 3 Dehydrofluorination of CF₃CHFCHF₂ to CF₃CF═CHF (E and ZIsomers) Over Carbonaceous Catalyst

A mixture of CF₃CHFCHF₂ and nitrogen were passed through the reactorfollowing the procedure of Example 1. The results of GC analysis of thereactor effluent are summarized in Table 5.

TABLE 5 Reactor Temp. CF₃CHFCHF₂ N₂ feed GC Area Percent (° C.) feed(mL/min) (mL/min) Z-CF₃CF═CHF E-CF₃CF═CHF CF₃CHFCHF₂ Unks 200 10 20 0.03ND 99.97 ND 250 10 20 0.2 0.03 99.8 ND 300 10 20 1.4 0.22 98.4 0.01 35010 20 5.4 0.96 93.1 0.5 400 10 20 38.1 9.0 51.7 1.1 400 10 10 37.9 8.751.6 1.8 400 10 5 42.6 9.5 46.7 1.2 400 10 40 13.2 2.5 71.6 12.7 ND =not detected Unks = unknowns

Example 4 Synthesis of CF₃CF═CH₂ by Dehydrofluorination With FluoridedAlumina Catalyst

A Hastelloy™ tube reactor (2.54 cm OD×2.17 cm ID×24.1 cm L) was filledwith 25 cc of gamma-alumina ground to 12-20 mesh (0.84 to 1.68 mm). Thecatalyst was activated by heating at 200° C. for 15 minutes under anitrogen purge and then reacted with a HF/N₂ mixture heated up to 425°C. to yield 16.7 gm of activated fluorided alumina.

At a temperature of 350° C., 10 sccm of nitrogen (1.7×10⁻⁷ m³/s) and 15sccm (2.5×10⁻⁷ m³/s) of CF₃CF₂CH₃ were mixed and flowed through thereactor. The temperature was then raised to 400° C., the flow rates heldconstant. The effluent for both temperatures was sampled and analyzed by¹⁹F NMR. Additionally, the effluent was analyzed by GC to determineconcentrations as listed in Table 6.

TABLE 6 CF₃CF₂CH₃ Temp., N₂ flow flow Concentrations, (Mole %) ° C.(sccm) (sccm) CF₃CF═CH₂ CF₃CF₂CH₃ Unks 350 10 15 84.2 12.8 3.0 400 10 1591.3 1.9 6.8 Unks = unknowns

Example 5 Synthesis of CF₃CF═CH₂ With Carbon Catalyst

Following the procedure of Example 3, a mixture of 10 sccm (1.7×10⁻⁷m³/s) of nitrogen and 15 sccm (2.5×10⁻⁷ m³/s) of CF₃CF₂CH₃ were passedthrough the reactor giving a contact time of 60 seconds. The flows werereduced to 5 sccm 8.3×10⁻⁸ m³/s) of nitrogen (and 7.5 sccm (1.3×10⁻⁷m³/s) of CF₃CF₂CH₃ giving a contact time of 120 seconds. The effluentwas sampled under both sets of conditions and analyzed by ¹⁹F NMR. Theeffluent compositions as determined by GC are listed in Table 7.

TABLE 7 CF₃CF₂CH₃ Temp., N₂ flow flow Concentrations, Mole % ° C. (sccm)(sccm) CF₃CF═CH₂ CF₃CF₂CH₃ Unks 400 10 15 6.0 93.9 0.1 400 5 7.5 22.876.4 0.8 Unks = unknowns

Example 6 Synthesis of CHF₂CF═CHF from CHF₂CF₂CH₂F

A 0.375 inch (0.95 cm) O.D. Hastelloy™ nickel alloy tube was chargedwith 7.0 grams (10 cc) of gamma-alumina ground to 12/20 mesh (0.84 to1.68 mm). The tube was purged with nitrogen (50 sccm, 8.3×10⁻⁷ m³/s) fortwenty minutes as the temperature was raised from 40° C. to 175° C. Thenitrogen flow was continued as anhydrous hydrogen fluoride (50 sccm,8.3×10⁻⁷ m³/s) was added to the reactor for about 1.5 hours. Thenitrogen flow was then reduced to 20 sccm (3.3×10⁻⁷ m³/s) and thehydrogen fluoride flow increased to 80 sccm (1.3×10⁻⁶ m³/s) as thetemperature in the tube was increased from 174° C. to 373° C. over thecourse of 3.7 hours. The nitrogen flow was then reduced to 10 sccm(1.7×10⁻⁷ m³/s) and the hydrogen fluoride flow was maintained at 80 sccm(1.3×10⁻⁶ m³/s) for one hour at 400° C. The reactor temperature was thenadjusted to 290° C. and the reactor purged with nitrogen.

CHF₂CF₂CH₂F was vaporized and fed to the reactor at such a rate as tomaintain a contact time with the catalyst of 120 seconds. No nitrogenco-feed was present. Gas chromatographic analyses of the reactoreffluent at three temperatures are listed in Table 8.

TABLE 8 Reactor GC Area Percent Temp, E and Z- ° C. CHF₂CF₂CH₂FCHF₂CHFCHF₂ CHF₂CF═CHF 275 72.3 5.5 22.0 325 40.8 6.9 51.7 375 27.0 3.268.9

Example 7 Synthesis of CF₃CH═CFCF₃

A Hastelloy™ nickel alloy reactor (2.54 cm OD×2.17 cm ID×24.1 cm L) wascharged with 13.5 g (25 mL) of spherical (8 mesh) three dimensionalmatrix porous carbonaceous material, as described in Example 1.

At a temperature of 300° C., 12.5 sccm of nitrogen (2.1×10⁻⁷ m³/s) and12.5 sccm (2.1×10⁻⁷ m³/s) of CF₃CHFCHFCH₃ were mixed and flowed throughthe reactor. The reactor temperature was raised to 350° C. and finallyto 400° C. and the effluent were analyzed by GC/MS at each temperature.The effluent composition is listed in Table 9.

TABLE 9 Reactor Temp., Mole percent ° C. CF₃CF═CFCF₃ E- andZ-CF₃CH═CFCF₃ CF₃CHFCHFCF₃ CF₃C≡CCF₃ unknowns 300 0.2 24.4 73.3 ND 2.1350 0.2 71.6 26.1 ND 2.1 400 — 90.1 8.3 0.4 1.2

Example 8 Synthesis of CH₂═CFCH₂CF₃ and E/Z—CF₃CH═CFCH₃

A Hastelloy™ nickel alloy reactor (2.54 cm OD×2.17 cm ID×24.1 cm L) wascharged with 13.5 g (25 mL) of spherical (8 mesh) three dimensionalmatrix porous carbonaceous material, as described in Example 1.

At a temperature of 350° C., 25 sccm of N₂ (4.2×10⁻⁷ m³/s) and 25 sccm(4.2×10⁻⁷ m³/s) of CF₃CH₂CF₂CH₃ were mixed and flowed through thereactor. The effluent was analyzed by GC/MS and the results are listedin Table 10.

TABLE 10 Component Mole Percent CH₂═CFCH₂CF₃ 14.5 E- and Z-CF₃CH═CFCH₃11.9 CF₃CH₂CF₂CH₃ 72.0 unknowns 1.6

Example 9 Dehydrofluorination of CF₃CHFCHFCF₂CF₃ to CF₃CH═CFCF₂CF₃ andCF₃CF═CHCF₂CF₃ Over Carbonaceous Catalyst

Following the procedure of Example 3, a mixture of nitrogen (10 mL/min,1.7×10⁻⁷ m³/s) and CF₃CHFCHFCF₂CF₃ (5 mL of liquid/hour) was passedthrough the reactor. GC analyses of the reactor effluent at severalconditions are summarized in Table 11. In Table 11, temp is temperature,unks is unknowns, and other HFCs include CHF₃, CF₃CHF₂, and CF₃CH₂F.

TABLE 11 Reactor N₂ GC Area Percent temp, flow, Other Other Other ° C.sccm Unks Z-CF₃CF═CHCF₂CF₃ Z-CF₃CH═CFCF₂CF₃ C₅HF₉s CF₃CHFCHFCF₂CF₃C₅H₂F₁₀s HFCs 200 20 1.47 12.9 29.6 0.36 55.0 0.65 0.08 200 20 2.05 10.724.3 0.29 62.1 0.47 0.09 250 20 2.24 28.1 59.6 1.30 1.01 7.43 0.09 25020 2.07 28.1 59.9 1.30 1.00 7.35 0.33 250 40 2.14 28.9 60.2 1.35 0.906.25 0.32

Example 10 Phase Studies of Mixtures of HF and E-CF₃CH═CHF

A phase study was performed for a composition consisting essentially ofE-CF₃CH═CHF and HF, wherein the composition was varied and the vaporpressures were measured at both 20° C. and 70° C. Based upon the datafrom the phase studies, azeotropic compositions at other temperature andpressures have been calculated.

Table 12 provides a compilation of experimental and calculatedazeotropic compositions for HF and E-CF₃CH═CHF at specified temperaturesand pressures.

TABLE 12 Temperature, Pressure, Mole % ° C. psi (kPA) Mole % HFE-CF₃CH═CHF −20 15.5 (107)   27.3 72.7 0 35.6 (242)   29.7 70.3 20 70.4(485)   30.7 69.3 40 127 (878)  31.5 68.5 60 215 (1482) 31.6 68.4 65 242(1669) 31.5 68.5 70 273 (1881) 31.4 68.6 75 307 (2117) 31.2 68.8 80 345(2376) 31.0 69.0 85 386 (2661) 30.7 69.3 90 431 (2972) 30.4 69.6 95 482(3323) 30.0 70.0 100 539 (3715) 29.5 70.5

Example 11 Phase Studies of Mixtures of HF and Z—CF₃CF═CHF

A phase study was performed for a composition consisting essentially ofZ—CF₃CF═CHF and HF, wherein the composition was varied and the vaporpressures were measured at both 19.5° C. and 70° C. Based upon the datafrom the phase studies, azeotrope compositions at other temperature andpressures have been calculated.

Table 13 provides a compilation of experimental and calculated azeotropecompositions for HF and Z—CF₃CF═CHF at specified temperatures andpressures.

TABLE 13 Temperature, Pressure, Mole % ° C. psi (kPa) Mole % HFZ-CF₃CF═CHF −25 12.8 (88.3)  31.0 69.0 −20 16.7 (115)   31.7 68.3 −1024.7 (170)   32.6 67.4 0 36.5 (252)   33.4 66.6 19.5 72.1 (497)   34.465.6 25 85.8 (592)   34.5 65.5 50 175 (1208) 35.0 65.0 75 323 (2226)35.2 64.8 77 335 (2308) 35.2 64.8 80 361 (2490) 35.3 64.7 85 403 (2777)35.3 64.7 90 448 (3090) 35.4 64.6 95 497 (3429) 35.4 64.6 100 551 (3799)35.5 64.5

Example 12 Phase Studies of Mixtures of HF and a Mixture ofZ—CF₃CH═CFCF₂CF₃ and Z—CF₃CF═CHCF₂CF₃

A phase study was performed for a composition consisting essentially ofa mixture of Z—CF₃CH═CFCF₂CF₃ and Z—CF₃CF═CHCF₂CF₃ and HF, wherein thecomposition was varied and the vapor pressures were measured at both 20°C. and 70° C. Based upon the data from the phase studies, azeotropecompositions at other temperature and pressures have been calculated.

Table 14 provides a compilation of experimental and calculated azeotropecompositions for HF and a mixture of Z—CF₃CH═CFCF₂CF₃ andZ—CF₃CF═CHCF₂CF₃ at specified temperatures and pressures.

TABLE 14 Mole % Temperature, Pressure, Mole % Z-CF₃CH═CFCF₂CF₃ and ° C.psi (kPa) HF Z-CF₃CF═CHCF₂CF₃ −20 4.1 (28.3) 88.6 11.4 −15 5.3 (36.5)87.8 12.2 −10 6.7 (46.2) 87.0 13.0 −5 8.5 (58.6) 86.2 13.8 0 10.6(73.1)  85.3 14.7 20 24.2 (167)   82.0 18.0 40 49.3 (340)   78.6 21.4 6092.8 (639)   75.1 24.9 65 108 (742)  74.2 25.8 70 124 (855)  73.4 26.675 143 (988)  72.5 27.5 80 165 (1136) 71.6 28.4 85 189 (1300) 70.6 29.490 217 (1495) 69.7 30.3 95 248 (1713) 68.6 31.4 100 285 (1965) 67.4 32.6

Example 13 Phase Studies of Mixtures of HF and CF₃CHFCHFCF₂CF₃

A phase study was performed for a composition consisting essentially ofCF₃CHFCHFCF₂CF₃ and HF, wherein the composition was varied and the vaporpressures were measured at both 30° C. and 80° C. Based upon the datafrom the phase studies, azeotrope compositions at other temperature andpressures have been calculated.

Table 15 provides a compilation of experimental and calculated azeotropecompositions for HF and CF₃CHFCHFCF₂CF₃ at specified temperatures andpressures.

TABLE 15 Temperature, Pressure, Mole % ° C. psi (kPa) Mole % HFCF₃CHFCHFCF₂CF₃ −20   3.0 (20.7) 97.3 2.7 0   7.7 (53.1) 95.5 4.5 2017.3 (119) 93.2 6.8 30 25.0 (172) 91.9 8.1 39.5 34.7 (239) 90.7 9.3 4035.3 (243) 90.6 9.4 60 66.6 (459) 87.8 12.2 65 77.3 (533) 87.0 13.0 7089.3 (616) 86.3 13.7 75  103 (710) 85.5 14.5 80  118 (814) 84.8 15.2 85 135 (931) 84.0 16.0 90   154 (1062) 83.3 16.7 95   175 (1207) 82.6 72.497.2   185 (1276) 82.2 17.8 100   198 (1365) 81.8 18.2

Example 14 Phase Studies of Mixtures of HF and CF₃CF═CH₂

A phase study was performed for a composition consisting essentially ofCF₃CF═CH₂ and HF, wherein the composition was varied and the vaporpressures were measured at both 9.3° C. and 44.4° C. Based upon the datafrom the phase studies, azeotrope compositions at other temperature andpressures have been calculated.

Table 16 provides a compilation of experimental and calculated azeotropecompositions for HF and CF₃CF═CH₂ at specified temperatures andpressures.

TABLE 16 Temperature, Pressure, Mole % ° C. psi (kPa) Mole % HFCF₃CF═CH₂ −20 23.2 (160)   19.3 80.7 −18.5 24.7 (170)   19.7 80.3 0 49.5(341)   23.0 77.0 9.3 67.6 (466)   24.4 75.6 20 94.6 (652)   25.7 74.340 167 (1151) 27.7 72.3 44.4 187 (1289) 28.0 72.0 60 278 (1917) 29.570.5 70 354 (2441) 30.3 69.7 71.2 365 (2517) 30.4 69.6 75 400 (2758)30.7 69.3 80 453 (3123) 31.1 68.9

Example 15 Phase Studies of Mixtures of HF and CF₃CH═CF₂

A phase study was performed for a composition consisting essentially ofCF₃CH═CF₂ and HF, wherein the composition was varied and the vaporpressures were measured at both 0.3° C. and 50.1° C. Based upon the datafrom the phase studies, azeotrope compositions at other temperature andpressures have been calculated.

Table 17 provides a compilation of experimental and calculated azeotropecompositions for HF and CF₃CH═CF₂ at specified temperatures andpressures.

TABLE 17 Temperature, Pressure, Mole % ° C. psi (kPa) Mole % HFCF₃CH═CF₂ −20 17.4 (120)   29.6 70.4 −17 19.7 (136)   29.9 70.1 −3 34.7(239)   31.0 69.0 0 38.8 (267)   30.9 69.1 0.3 39.2 (270)   30.9 69.13.9 44.7 (308)   31.0 69.0 20 76.7 (529)   32.8 67.2 40 139 (958)  34.066.0 50.1 183 (1262) 34.5 65.5 60 236 (1627) 34.9 65.1 65 268 (1848)35.1 64.9 70 304 (2096) 35.3 64.7 71.5 314.7 (2170)   35.4 64.6 75 344(2372) 35.6 64.4 80 389 (2682) 35.3 64.7 85 441 (3041) 36.0 64.0 90 524(3613) 36.9 63.1 95 629 (4337) 37.4 62.6 100 745 (5137) 38.0 62.0

Example 16 Phase Studies of Mixtures of HF and a Mixture ofZ—C₂F₅CF═CHCF₂C₂F₅ and Z—C₂F₅CH═CFCF₂C₂F₅

A phase study was performed for a composition consisting essentially ofHF and a mixture of Z—C₂F₅CF═CHCF₂C₂F₅ and Z—C₂F₅CH═CFCF₂C₂F₅, whereinthe composition was varied and the vapor pressures were measured at both19.9° C. and 69.6° C. Based upon the data from the phase studies,azeotrope compositions at other temperature and pressures have beencalculated.

Table 18 provides a compilation of experimental and calculated azeotropecompositions for HF and a mixture of Z—C₂F₅CF═CHCF₂C₂F₅ andZ—C₂F₅CH═CFCF₂C₂F₅ at specified temperatures and pressures.

TABLE 18 Mole % Temperature, Pressure, Mole % Z-C₂F₅CF═CHCF₂C₂F₅ ° C.psi (kPa) HF and Z-C₂F₅CH═CFCF₂C₂F₅ −20   2.9 (20.0) 98.7 1.3 −15   3.7(25.5) 98.5 1.5 −10   4.7 (32.4) 98.3 1.7 −5   5.9 (40.7) 98.1 1.9 0  7.3 (50.3) 97.9 2.1 19.9 16.3 (112) 96.7 3.3 20 16.3 (112) 96.7 3.325.1 19.7 (136) 96.4 3.6 40 33.2 (229) 95.4 4.6 60 62.3 (430) 93.9 6.165 72.1 (497) 93.5 6.5 69.6 82.2 (567) 93.1 6.9 70 83.3 (574) 93.1 6.975 95.7 (660) 92.7 7.3 80  110 (758) 92.3 7.7 85  125 (862) 91.9 8.1 90 143 (986) 91.5 8.5 95   162 (1117) 91.2 8.8 100   183 (1262) 90.8 9.2108.4   225 (1551) 90.3 9.7

Example 17 Phase Studies of Mixtures of HF and C₂F₅CHFCHFCF₂C₂F₅

A phase study was performed for a composition consisting essentially ofC₂F₅CHFCHFCF₂C₂F₅ and HF, wherein the composition was varied and thevapor pressures were measured at both 30.8° C. and 80.2° C. Based uponthe data from the phase studies, azeotrope compositions at othertemperature and pressures have been calculated.

Table 19 provides a compilation of experimental and calculated azeotropecompositions for HF and C₂F₅CHFCHFCF₂C₂F₅ at specified temperatures andpressures.

TABLE 19 Temperature, Pressure, Mole % ° C. psi (kPa) Mole % HFC₂F₅CHFCHFCF₂C₂F₅ 13.5  11.9 (82.0) <100 0.003 14  12.1 (83.4) 99.9 0.114.5  12.3 (84.8) 99.9 0.1 15  12.6 (86.9) 99.8 0.2 20 15.1 (104) 99.30.7 25 18.1 (125) 98.8 1.2 27.4 19.7 (136) 98.6 1.4 30 21.6 (149) 98.51.5 30.8 22.2 (153) 98.5 1.5 40 30.3 (209) 98.2 1.8 50 41.7 (288) 97.72.3 60 56.5 (390) 97.3 2.7 70 75.3 (519) 96.8 3.2 80 99.1 (683) 96.3 3.780.2 99.6 (687) 96.3 3.7 90  129 (889) 95.8 4.2 99.8   165 (1138) 95.44.6 100   165 (1138) 95.4 4.6 110   210 (1484) 95.0 5.0 120   264 (1820)94.7 5.3

Example 18 Azeotropic Distillation for Separation of E-CF₃CH═CHF fromCF₃CH₂CHF₂

A mixture of HF, E-CF₃CH═CHF, and CF₃CH₂CHF₂ is fed to a distillationcolumn for the purpose of purification of the E-CF₃CH═CHF. The data inTable 20 were obtained by calculation using measured and calculatedthermodynamic properties.

TABLE 20 Component or Column overhead variable Column feed (distillate)Column bottoms CF₃CH₂CHF₂, 17.6 0.7 ppm 100   mol % E-CF₃CH═CHF, 76.592.9 3 ppm mol % HF, mol %  5.9  7.1 — Temp, ° C. — −6.8 31.1 Pressure,psi — 24.7 (170) 26.7 (184) (kPa)

Example 19 Azeotropic Distillation for Separation of Z—CF₃CF═CHF fromCF₃CHFCHF₂

A mixture of HF, Z—CF₃CF═CHF, and CF₃CHFCHF₂ is fed to a distillationcolumn for the purpose of purification of the Z—CF₃CF═CHF. The data inTable 21 were obtained by calculation using measured and calculatedthermodynamic properties.

TABLE 21 Component or Column Column overhead variable feed (distillate)Column bottoms CF₃CHFCHF₂, 24.4 1 ppm 99.99 mol % Z-CF₃CF═CHF, 51.2 67.768 ppm mol % HF, mol % 24.4 32.3 trace Temp, ° C. — −8.3 21.8  Pressure,psi — 24.7 (170) 26.7 (184) (kPa)

Example 20 Azeotropic Distillation for Separation of Z—CF₃CH═CFCF₂CF₃and Z—CF₃CF═CHCF₂CF₃ from CF₃CHFCHFCF₂CF₃

A mixture of HF, Z—CF₃CH═CFCF₂CF₃ and Z—CF₃CF═CHCF₂CF₃, andCF₃CHFCHFCF₂CF₃ is fed to a distillation column for the purpose ofpurification of Z—CF₃CH═CFCF₂CF₃ and Z—CF₃CF═CHCF₂CF₃. The data in Table22 were obtained by calculation using measured and calculatedthermodynamic properties.

TABLE 22 Component or Column overhead Column variable Column feed(distillate) bottoms CF₃CHFCHFCF₂CF₃, 33.4 1 ppm 100   mol %Z-CF₃CH═CFCF₂CF₃ 33.3 50.0 2 ppm and Z-CF₃CF═CHCF₂CF₃, mol % HF, mol %33.3 50.0 — Temp, ° C. — 30.0 21.8 Pressure, psi (kPa) — 19.7 (136) 21.7(150)

Example 21 Azeotropic Distillation for Separation of CF₃CF═CH₂ FromCF₃CF₂CH₃

A mixture of HF, CF₃CF═CH₂, and CF₃CF₂CH₃ is fed to a distillationcolumn for the purpose of purification of CF₃CF═CH₂. The data in Table23 were obtained by calculation using measured and calculatedthermodynamic properties.

TABLE 23 Component or Column overhead variable Column feed (distillate)Column bottoms CF₃CF₂CH₃, 27.3 10 ppm 100 mol % CF₃CF═CH₂, 63.6 87.5 27ppm mol % HF, mol % 9.1 12.5 — Temp, ° C. — −17.2 −2.7 Pressure, psi —24.7 (170) 26.7 (184) (kPa)

Example 22 Azeotropic Distillation for Separation of CF₃CH═CF₂ FromCF₃CH₂CF₃

A mixture of HF, CF₃CH═CF₂, and CF₃CH₂CF₃ is fed to a distillationcolumn for the purpose of purification of the CF₃CH═CF₂. The data inTable 24 were obtained by calculation using measured and calculatedthermodynamic properties.

TABLE 24 Component or Column overhead variable Column feed (distillate)Column bottoms CF₃CH₂CF₃, 17.6 10 ppm 99.99 mol % CF₃CH═CF₂, 76.5 92.978 ppm mol % HF, mol % 5.9 7.1 — Temp, ° C. — −15.4 8.3 Pressure, psi —19.7 (136) 21.7 (150) (kPa)

Example 23 Azeotropic Distillation for Separation of Z—C₂F₅CF═CHCF₂C₂F₅and Z—C₂F₅CH═CFCF₂C₂F₅ From C₂F₅CHFCHFCF₂C₂F₅

A mixture of HF, Z—C₂F₅CF═CHCF₂C₂F₅ and Z—C₂F₅CH═CFCF₂C₂F₅, andC₂F₅CHFCHFCF₂C₂F₅ is fed to a distillation column for the purpose ofpurification of Z—C₂F₅CF═CHCF₂C₂F₅ and Z—C₂F₅CH═CFCF₂C₂F₅. The data inTable 25 were obtained by calculation using measured and calculatedthermodynamic properties.

TABLE 25 Column overhead Component or variable Column feed (distillate)Column bottoms C₂F₅CHFCHFCF₂C₂F₅, 33.4 1 ppm 100 mol %Z-C₂F₅CF═CHCF₂C₂F₅ 33.3 50.0 8 ppm and Z-C₂F₅CH═CFCF₂C₂F₅, mol % HF, mol% 33.3 50.0 — Temp, ° C. — 75.4 107 Pressure, psi (kPa) — 19.7 (136)21.7 (150)

Example 24 Two-Column Azeotropic Distillation for Separation ofE-CF₃CH═CHF From HF

A mixture of HF and E-CF₃CH═CHF is fed to a distillation set-upcomprising 2 columns in series, the first at high pressure (HP) and thesecond at low pressure (LP). The data in Table 26 were obtained bycalculation using measured and calculated thermodynamic properties. Thenumbers at the top of the columns refer to FIG. 1.

TABLE 26 570 585 540 Column 566 Column 586 Compound Feed (510)E-CF₃CH═CHF (520) HF or variable Mixture distillate product distillateproduct E-CF₃CH═CHF, 76.0 69.0 100 72.0 — mol % HF, mol % 24.0 31.0 —28.0 100 Temp, ° C. — 68.6 76.1 −18.3 26.2 Pres, psi — 265 (1827) 267(1841) 16.7 (115) 18.7 (129) (kPa)

Example 25 Two-Column Azeotropic Distillation for Separation ofZ—CF₃CF═CHF From HF

A mixture of HF and Z-HFC-1225ye is fed to a distillation process forthe purpose of purification of the Z-HFC-1225ye. The data in Table 27were obtained by calculation using measured and calculated thermodynamicproperties. The numbers at the top of the columns refer to FIG. 1.

TABLE 27 570 585 540 Column 566 Column 586 Compound or Feed (510)Z-CF₃CF═CHF (520) HF variable Mixture distillate product distillateproduct HF, mol % 26.7 35.0 trace 32.0 100 Z-CF₃CF═CHF, 73.3 65.0 10068.0 — mol % Temp., ° C. — 76.6 86.0 −19.2 26.2 Pres., psi (kPa) — 334.7(2307) 336.7 (2321) 16.7 (115) 18.7 (129)

Example 26 Two-Column Azeotropic Distillation for Separation ofZ—CF₃CH═CFCF₂CF₃ and Z—CF₃CF═CHCF₂CF₃ From HF

A mixture of HF and Z—CF₃CH═CFCF₂CF₃ and Z—CF₃CF═CHCF₂CF₃ is fed to adistillation process for the purpose of purification of theZ—CF₃CH═CFCF₂CF₃ and Z—CF₃CF═CHCF₂CF₃. The data in Table 28 wereobtained by calculation using measured and calculated thermodynamicproperties. The numbers at the top of the columns refer to FIG. 1.

TABLE 28 570 585 586 540 Column 566 Column Z-CF₃CH═CFCF₂CF₃ Compound orFeed (510) HF (520) and Z-CF₃CF═CHCF₂CF₃ variable Mixture distillateproduct distillate product HF, mol % 73.9 70.0 100 82.5 100Z-CF₃CH═CFCF₂CF₃ 26.1 30.0 — 17.5 — and Z-CF₃CF═CHCF₂CF₃, mol % Temp., °C. — 91.7 117.5 14.9 39.8 Pres., psi (kPa) — 224.7 (1549) 226.7 (1563)19.7 (136) 21.7 (150)

Example 27 Two-Column Azeotropic Distillation for Separation ofCF₃CF═CH₂From HF

A mixture of HF and CF₃CF═CH₂ is fed to a distillation process for thepurpose of purification of the CF₃CF═CH₂. The data in Table 29 wereobtained by calculation using measured and calculated thermodynamicproperties. The numbers at the top of the columns refer to FIG. 1.

TABLE 29 570 585 Column 566 Column 586 Compound 540 (510) CF₃CF═CH₂(520) HF or variable Feed Mixture distillate product distillate productHF, mol % 16.0 30.0 — 20.0 100 CF₃CF═CH₂, 84.0 70.0 100 80.0 — mol %Temp., — 71.2 80.2 −18.4 36.9 ° C. Pres., — 364.7 (2515) 366.7 (2528)24.7 (170) 26.7 (184) psi (kPa)

Example 28 Two-Column Azeotropic Distillation for Separation of CF₃CH═CFFrom HF

A mixture of HF and CF₃CH═CF₂ is fed to a distillation process for thepurpose of purification of the CF₃CH═CF₂. The data in Table 30 wereobtained by calculation using measured and calculated thermodynamicproperties. The numbers at the top of the columns refer to FIG. 1.

TABLE 30 570 585 Column 566 Column 586 Compound 540 (510) CF₃CH═CF₂(520) HF or variable Feed Mixture distillate product distillate productHF, mol % 30.4 24.1 — 30.5 100 CF₃CH═CF₂, 69.6 75.9 100 69.5 — mol %Temp., — 71.5 80.1 −17.1 30.6 ° C. Pres., — 314.7 (2170) 316.7 (2184)19.7 (136) 21.7 (150) psi (kPa)

Example 29 Two-Column Azeotropic Distillation for Separation ofZ—C₂F₅CF═CHCF₂C₂F₅ and Z—C₂F₅CH═CFCF₂C₂F₅ From HF

A mixture of HF and Z—C₂F₅CF═CHCF₂C₂F₅ and Z—C₂F₅CH═CFCF₂C₂F₅ is fed toa distillation process for the purpose of purification of theZ—C₂F₅CF═CHCF₂C₂F₅ and Z—C₂F₅CH═CFCF₂C₂F₅. The data in Table 31 wereobtained by calculation using measured and calculated thermodynamicproperties. The numbers at the top of the columns refer to FIG. 1.

TABLE 31 566 570 Z-C₂F₅CF═CHCF₂C₂F₅ 585 540 Column and Column 586Compound or Feed (510) Z-C₂F₅CH═CFCF₂C₂F₅ (520) HF variable Mixturedistillate product distillate product HF, mol % 93.9 95.8 100 91.0 100Z-C₂F₅CF═CHCF₂C₂F₅  6.1 4.2 — 9.0 — and Z-C₂F₅CH═CFCF₂C₂F₅, mol % Temp.,° C. — 26.9 84.8 109 117.5 Pres., psi (kPa) — 19.7 (136) 21.7 (150)224.7 (1549) 226.7 (1563)

Examples 30-33

Examples 30-33 use one of three reactors:

Reactor A:

Inconel® 600 tube (this alloy is about 76 wt % nickel), 18 in (45.7 cm)long×1.0 in (2.5 cm) outer diameter×0.84 in (2.1 cm) inner diameter.Tube wall thickness is 0.16 in (0.41 cm). The preheat zone is 7 in (17.8cm) long. The reaction zone is 2 in (5.1 cm) long. The quench zone is 7in (17.8 cm) long. The tube is heated with 1 in (2.5 cm) diameterceramic band heaters. The leads of a 7-point thermocouple aredistributed long the length of the tube, with some in the middle of thereactor zone (to measure gas temperature).

Reactor B:

Schedule 80 Nickel 200 tube with an Inconel® 617 overlay, 18 in (45.7cm) long, 1.5 in (3.8 cm) outer diameter, 0.84 in (2.1 cm) innerdiameter. The reaction zone is 2 in (5.1 cm) long. The reactor zone isheated with an 8.5 in (21.6 cm) long×2.5 in (6.35 cm) split tubefurnace. The leads of a 7-point thermocouple are distributed long thelength of the tube, with some in the middle of the reactor zone (tomeasure gas temperature).

Reactor C:

Hastelloy® C276 with gold lining. Length 5 in (12.7 cm)×0.50 in (1.3 cm)outer diameter×0.35 in (0.89 cm) inner diameter. The wall thickness is0.15 in (3.8 mm). The thickness of the gold lining is 0.03 in (0.08 cm).The reactor zone is 2 in (5.1 cm) long and is heated with a ceramic bandheater.

Example 30

Reactor A (Inconel® 600 reaction surface) is used. The reactor inlet gastemperature (“Reactor Inlet T Gas” in Table 1) is the reactiontemperature. Two runs are made at reaction temperatures of 724° C. and725° C., respectively. In Run A, the reactant feed is undiluted withinert gas. In Run B, helium and reactant are fed in the ratio of 1.4:1.The benefit of the inert gas diluent is seen in the improved yield ofRun B (80%) over that of Run A (71%). A lower concentration offluorocarbon byproducts are made in Run B. Results are summarized inTable 32. Note that “sccm” in the table stands for “standard cubiccentimeters per minute”.

TABLE 32 A B Reactor Conditions, Feeds Preheat Control T setting 700° C.700° C. Preheat Gas T 1″ 545° C. 572° C. Preheat Gas T 2″ 635° C. 655°C. Preheat Gas T 3″ 690° C. 696° C. Preheat Gas T 4″ 718° C. 720° C.Reactor Control T setting 700° C. 700° C. Reactor Inlet T wall 711° C.710° C. Reactor Middle T wall 700° C. 700° C. Reactor Exit T wall 622°C. 623° C. Reactor Inlet T gas 724° C. 725° C. Reactor Middle T gas 714°C. 716° C. Reactor Exit T gas 675° C. 673° C. HFC-236fa Feed sccm 25sccm 25 sccm Helium Feed sccm  0 sccm 35 sccm Residence Time in ReactionZone 42 18 (seconds) Gas Chromatograph Results in Mole % CHCF₃ (HFC-23)4.5 2.1 CF₃CH═CF₂ (HFC-1225zc) 51.6 47.7 Octafluorocyclobutane(PFC-C318) 1.8 2.0 CF₃CH₂CF₃ (HFC-236fa) 27.5 40.3 C₄H₂F₆ (HFC-1336) 1.80.7 C₄HF₇ (HFC-1327) 1.7 1.2 C₄HF₉ (HFC-329) 4.2 2.1 Other 3.1 2.1Unknown 3.8 1.8 Conversion (%) 72.5 59.7 Yield (%) 71 80

Example 31

Reactor A (Inconel® 600 reaction surface) is used in this study of theeffect of temperature on conversion and yield. Run A is made at reactortemperature of 600° C. Runs B and C are made at 699° C. and 692° C.,respectively. Runs A and B are diluted 4:1 with helium. Run C isundiluted. Run A (600° C.) conversion is low at 0.3%. Runs B and C(690-700° C.) have higher conversion, though still low compared to theconversion seen in Example 30, which was run at 725° C. and appreciablylonger reaction zone residence times. Yields are reported, however arenot reliable for such low conversions. The dependence of conversion ontemperature and reaction zone residence time is plain from theseexperiments. Results are summarized in Table 33.

TABLE 33 A B C Reactor Conditions, Feeds Preheat Control T setting 600700 700 (° C.) Preheat Gas T 1″ (° C.) 417 497 443 Preheat Gas T 2″ (°C.) 511 604 546 Preheat Gas T 3″ (° C.) 563 660 623 Preheat Gas T 4″ (°C.) 592 691 676 Reactor Control T setting 601 700 700 (° C.) ReactorInlet T wall (° C.) 615 718 722 Reactor Middle T wall (° C.) 601 700 700Reactor Exit T wall (° C.) 566 661 653 Reactor Inlet T gas (° C.) 600699 692 Reactor Middle T gas (° C.) 588 684 665 Reactor Exit T gas (°C.) 560 650 609 Helium Feed sccm 400 400 0 HFC-236fa Feed sccm 100 100200 Residence Time in Reaction 2 2 5 Zone (seconds) Gas ChromatographResults in Mole % CHCF₃ (HFC-23) 0.0 0.0 0.1 CHF═CF₂ (HFC-1123) 0.0 0.00.1 CF₃CH═CF₂ (HFC-1225zc) 0.1 2.1 4.4 CF₃CH₂CF₃(HFC-236fa) 99.7 97.695.3 Other (<1%) 0.2 0.2 0.3 Conversion (%) 0.3 2.4 4.7 Yield (%) 3387.5 93.6

Example 32

Reactor B (Nickel 200 reaction surface) is used. In this reactor thereactor temperature is the reactor center gas temperature (“ReactorCenter Gas T” in Table 3). Runs A, B, and C are made at 800° C. withhelium:reactant ratios of 0:1, 1:1, and 2:1, respectively. At thesetemperatures, higher than in Example 30, and at comparable reaction zoneresidence times, on the nickel surface, conversions are as high, andyields higher. In pyrolyses, higher temperatures generally lead to loweryields because of increased rates of undesirable side reactions givingunwanted byproducts. That this is not seen in Example 32 is testimony tothe superiority of the nickel reaction surface to the nickel alloyreaction surface of Example 30. Further support for this conclusion isfound in Run D, made at 850° C. with 4:1 helium dilution. Conversion ishigh at 76.9%, and the yield is 90.5%, the best of any of the Example 32runs. Results are summarized in Table 34.

TABLE 34 A B C D Reactor Conditions, Feeds Reactor Control T setting 839834 832 885 (° C.) Reactor Inlet T wall (° C.) 812 806 804 853 ReactorMiddle 831 826 824 877 T wall (° C.) Reactor Exit T wall (° C.) 808 805804 855 Preheat Gas T 1″ (° C.) 658 666 669 707 Reactor Inlet gas 736740 741 786 T 2″ (° C.) Reactor Inlet gas 779 780 781 829 T 3″ (° C.)Reactor Center gas T 4″ 800 800 800 850 (° C.) Reactor Exit gas 800 800799 851 T 5″ (° C.) Reactor Exit gas 776 777 777 829 T 6″ (° C.) Exitgas T 7″ (° C.) 738 741 740 791 HFC-236fa Feed sccm 200 200 200 200 HeFeed sccm 0 200 400 800 Residence Time in Reaction 5 3 2 1 Zone(seconds) GC Results in Mole % CHCF₃ (HFC-23) 4.1 2.5 2.0 2.5 CHF═CF₂(HFC-1123) 0.7 1.0 1.0 1.4 CF₃CH═CF₂ 60.8 50.6 45.3 69.6 (HFC-1225zc)CF₃CH₂CF₃ (HFC-236fa) 28.2 37.7 50.2 23.1 C₄H₂F₆ (HFC-1336) 1.3 0.6 0.40.0 Other (<1% produced) 2.1 1.0 1.1 2.1 Unknown 2.8 6.6 0.0 1.2Conversion (%) 71.8 62.3 49.8 76.9 Yield (%) 84.7 81.2 90.9 90.5

Example 33

Reactor C (gold reaction surface). Like nickel, the gold surface giveshigh yields and therefore reduced side reactions producing unwantedbyproducts. The inert gas diluent effect (reduction) on conversion isless on gold than on nickel or nickel alloy surfaces. At 800° C. (Runs Aand B) conversions are lower than those of Runs B and C of Example 32but the average yield is higher. Results are summarized in Table 35.

TABLE 35 Reactor Conditions, Feeds A B C D E F Reactor Temp (° C.) 800800 700 700 600 600 He Feed sccm 15 20 15 20 15 20 HFC-236fa Feed sccm10 5 10 5 10 5 Residence Time in 8 8 8 8 8 8 Reaction Zone (seconds) GCMole % CHF₃ and CH₂F₂ 1.9 1.9 0.1 0.1 ND* ND CHF═CF₂ (HFC-1123) 0.8 0.9ND ND ND ND CF₃CH₃ (HFC-143a) 0.2 0.2 ND ND ND ND CF₃CH═CF₂ (HFC- 33.336.6 1.7 1.8 0.2 0.1 1225zc) CF₃CHFCF₃ (HFC- 0.2 0.2 0.1 0.1 0.1 0.1227ea) CF₃CH₂CF₃ (HFC-236fa) 61.9 58.4 97.6 97.6 99.4 99.5 Unknown 0.60.5 0.3 0.1 0.2 0.1 Conversion (%) 38.1 41.6 2.4 2.4 0.6 0.5 Yield (%)87.4 88.0 71 75 33 20 *ND = not detected

Examples 30-33 show the specificity of the pyrolysis according to thisinvention, which gives the product CF₃CH═CF₂ in good yield at goodconversion with only small amounts of unwanted byproducts. Nickel issuperior to nickel alloy as the reaction surface in giving higher yieldsof product. Gold is superior to nickel.

Conversions are low up to about 700° C., being good at 725° C. and abovewith no deterioration in performance even at 850° C.

1. A process for the purification of a hydrofluoroolefin compoundcontaining 3 to 8 carbon atoms, from a mixture of hydrofluoroolefin,hydrofluorocarbon, and hydrogen fluoride, said process comprising: a)subjecting said mixture to a first distillation step to form a firstdistillate composition comprising an azeotrope or near-azeotropecomposition containing hydrofluoroolefin and hydrogen fluoride and afirst bottoms composition comprising hydrofluorocarbon; b) subjectingsaid first distillate to a second distillation step from which acomposition enriched in either (i) hydrogen fluoride or (ii)hydrofluoroolefin is removed as a second distillate composition with asecond bottoms composition being enriched in the other of saidcomponents (i) or (ii); and c) subjecting said second distillatecomposition to a third distillation step conducted at a differentpressure than the second distillation step in which the componentenriched in the second bottoms composition in (b) is removed as a thirddistillate composition with the third bottoms composition of the thirddistillation step enriched in the same component that was enriched inthe second distillate composition, wherein the hydrofluoroolefin andhydrofluorocarbon are CF₃CF₂CH₂F and CF₃CF═CHF; CF₃CHFCH₂F andCF₃CF═CH₂; CHF₂CF₂CH₂F and CHF₂CF═CHF; CHF₂CHFCHF₂ and CHF₂CF═CHF;CH₂FCF₂CH₂F and CH₂FCF═CHF; CH₃CF₂CHF₂ and CHF₂CF═CH₂; CHF₂CHFCH₂F andCHF₂CF═CH₂; CF₃CHFCH₃ and CF₃CH═CH₂; CF₃CH₂CH₂F and CF₃CH═CH₂;CHF₂CH₂CHF₂ and CHF₂CH═CHF; CH₂FCF₂CF₂CF₃ and CHF═CFCF₂CF₃;CF₃CHFCF₂CHF₂ and CF₃CF═CFCHF₂; CF₃CH₂CF₂CF₃ and CF₃CH═CFCF₃;CF₃CHFCHFCF₃ and CF₃CH═CFCF₃; CH₃CF₂CF₂CF₃ and CH₂═CFCF₂CF₃;CF₃CHFCF₂CH₂F and CF₃CF═CFCH₂F; CH₂FCF₂CF₂CHF₂ and CHF═CFCF₂CHF₂;CHF₂CH₂CF₂CF₃ and CHF₂CH═CFCF₃; CHF₂CF₂CH₂CF₃ and CHF₂CF═CHCF₃;CHF₂CHFCHFCF₃ and CHF₂CF═CHCF₃, CHF₂CH═CFCF₃, or mixtures thereof;CHF₂CHFCF₂CHF₂ and CHF₂CF═CFCHF₂; CF₃CH₂CHFCF₃ and CF₃CH═CHCF₃;CHF₂CH(CF₃)₂ and CHF═C(CF₃)₂; CH₂FCF(CF₃)₂ and CHF═C(CF₃)₂;CF₃CF₂CH₂CF₂CF₃ and CF₃CF₂CH═CFCF₃; CF₃CH₂CF₂CF₂CF₃ and CF₃CH═CFCF₂CF₃;CF₃CH₂CHFCF₂CF₃ and CF₃CH═CHCF₂CF₃; CF₃CHFCH₂CF₂CF₃ and CF₃CH═CHCF₂CF₃;CH₃CF₂CF₂CF₂CHF₂ and CH₂═CFCF₂CF₂CHF₂; CF₃CH₂CF₂CH₂CF₃ andCF₃CH═CFCH₂CF₃; CF₃CF₂CHFCHFCF₂CF₃ and CF₃CF₂CH═CFCF₂CF₃;CH₂FCHFCF₂CF₂CF₂CF₃ and CH₂═CFCF₂CF₂CF₂CF₃; CF₃CH₂CHFCF₂CF₂CF₃ andCF₃CH═CHCF₂CF₂CF₃; CF₃CHFCH₂CF₂CF₂CF₃ and CF₃CH═CHCF₂CF₂CF₃;CF₃CH₂CF₂CF₂CH₂CF₃ and CF₃CH═CFCF₂CH₂CF₃; CF₃CF₂CH₂CH₂CF₂CF₃ andCF₃CF═CHCH₂CF₂CF₃; CF₃CHFCHFCF₂CF₂C₂F₅ and CF₃CF═CHCF₂CF₂C₂F₅,CF₃CH═CFCF₂CF₂C₂F₅, or mixtures thereof; C₂F₅CHFCHFCF₂CF₂C₂F₅ andC₂F₅CF═CHCF₂CF₂C₂F₅, C₂F₅CH═CFCF₂CF₂C₂F₅, or mixtures thereof;C₂F₅CF₂CHFCHFCF₂C₂F₅ and C₂F₅CF₂CF═CHCF₂C₂F₅; cyclo-CF₂CF₂CF₂CH₂— andcyclo-CF₂CF₂CF═CH—; cyclo-CF₂CF₂CHFCHF— and cyclo-CF₂CF₂CF═CH—;cyclo-CF₂CF₂CH₂CH₂— and cyclo-CF₂CH₂CH═CF—; cyclo-CF₂CF₂CF₂CHFCHF— andcyclo-CF₂CF₂CF₂CF═CH—; cyclo-CF₂CF₂CF₂CF₂CHFCHF— andcyclo-CF₂CF₂CF₂CF₂CF═CH—; CF₃CF₂CH₂CH₃ and CF₃CF═CHCH₃; CF₃CH₂CF₂CH₃ andCF₃CH═CFCH₃; CH₂FCH₂CHFCF₃ and CH₂FCH═CHCF₃; CH₂FCHFCH₂CF₃ andCH₂FCH═CHCF₃; CH₃CF(CF₃)₂ and CH₂═C(CF₃)₂; CH₂FCH(CF₃)₂ and CH₂═C(CF₃)₂;CHF₂CF(CHF₂)₂ and CF₂═C(CHF₂)₂; CHF₂CH(CHF₂)₂ and CHF═C(CHF₂)₂;CH₃CF(CHF₂)₂ and CH₂═C(CHF₂)₂; CH₂FCH(CH₂F)CF₃ and CH₂═C(CH₂F)CF₃;CH₂FCH(CHF₂)₂ and CH₂═C(CHF₂)₂; CH₃CF₂CF₂CF₂CF₃ and CH₂═CFCF₂CF₂CF₃;CHF₂CF₂CF₂CHFCH₃ and CHF₂CF₂CF═CFCH₃; CF₃CF₂CF₂CH₂CH₃ andCF₃CF₂CF═CHCH₃; (CF₃)₂CFCH₂CF₃ and (CF₃)₂C═CHCF₃; (CF₃)₂CHCHFCF₃ and(CF₃)₂C═CHCF₃; (CF₃)₂CFCHFCHF₂ and (CF₃)₂C═CFCHF₂; CF₃CF₂CH₂CHFCF₂CF₃and CF₃CF₂CH═CHCF₂CF₃; CH₃CH₂CF₂CF₂CF₂CF₃ and CH₃CH═CFCF₂CF₂CF₃;CF₃CF₂CF₂CH₂CHFCH₃ and CF₃CF₂CF₂CH═CHCH₃; (CF₃)₂CFCF₂CH₂CH₃ and(CF₃)₂CFCF═CHCH₃; (CF₃)₂CFCH₂CH₂CH₃ and (CF₃)₂C═CHCH₂CH₃;(CF₃)₂CHCHFCF₂CF₃ and (CF₃)₂C═CHCF₂CF₃; (CF₃)₂CFCHFCHFCF₃ and(CF₃)₂C═CFCHFCF₃, (CF₃)₂CFCF═CHCF₃, (CF₃)₂CFCH═CFCF₃, or mixturesthereof; (CF₃)₂CHCH₂CF₂CF₃ and (CF₃)₂CHCH═CFCF₃; (CF₃)₂CFCH(CH₃)₂ and(CF₃)₂C═C(CH₃)₂; (CH₃)₂CHCF₂CF₂CF₃ and (CH₃)₂C═CFCF₂CF₃;C₂F₅CHFCH₂CF₂C₂F₅ and C₂F₅CH═CHCF₂C₂F₅; C₂F₅CH₂CHFCF₂C₂F₅ andC₂F₅CH═CHCF₂C₂F₅; CF₃CHFCH₂CF₂CF₂C₂F₅ and CF₃CH═CHCF₂CF₂C₂F₅;CF₃CH₂CHFCF₂CF₂C₂F₅ and CF₃CH═CHCF₂CF₂C₂F₅; CF₃CF₂CF₂CF₂CF₂CH₂CH₃ andCF₃CF₂CF₂CF₂CF═CHCH₃; CF₃CF₂CF₂CF₂CH₂CH₂CH₃ and CF₃CF₂CF₂CF═CHCH₂CH₃; or(CH₃)₂CHCF₂CF₂CF₂CF₃ and (CH₃)₂C═CFCF₂CF₂CF₃.
 2. The process of claim 1,further comprising recycling at least some portion of said secondbottoms composition or said third bottoms composition to said firstdistillation step.
 3. The process of claim 1 wherein said first bottomscomposition comprises hydrofluorocarbon essentially free of hydrogenfluoride.
 4. The process of claim 1 wherein said second bottoms or saidthird bottoms composition comprises hydrofluoroolefin essentially freeof hydrogen fluoride.
 5. The process of claim 1 wherein said secondbottoms composition or said third bottoms composition comprises hydrogenfluoride essentially free of hydrofluoroolefin.